WorldWideScience

Sample records for satellite system post-launch

  1. Post launch calibration and testing of the Geostationary Lightning Mapper on GOES-R satellite

    Science.gov (United States)

    Rafal, Marc; Clarke, Jared T.; Cholvibul, Ruth W.

    2016-05-01

    The Geostationary Operational Environmental Satellite R (GOES-R) series is the planned next generation of operational weather satellites for the United States National Oceanic and Atmospheric Administration (NOAA). The National Aeronautics and Space Administration (NASA) is procuring the GOES-R spacecraft and instruments with the first launch of the GOES-R series planned for October 2016. Included in the GOES-R Instrument suite is the Geostationary Lightning Mapper (GLM). GLM is a single-channel, near-infrared optical detector that can sense extremely brief (800 μs) transient changes in the atmosphere, indicating the presence of lightning. GLM will measure total lightning activity continuously over the Americas and adjacent ocean regions with near-uniform spatial resolution of approximately 10 km. Due to its large CCD (1372x1300 pixels), high frame rate, sensitivity and onboard event filtering, GLM will require extensive post launch characterization and calibration. Daytime and nighttime images will be used to characterize both image quality criteria inherent to GLM as a space-based optic system (focus, stray light, crosstalk, solar glint) and programmable image processing criteria (dark offsets, gain, noise, linearity, dynamic range). In addition ground data filtering will be adjusted based on lightning-specific phenomenology (coherence) to isolate real from false transients with their own characteristics. These parameters will be updated, as needed, on orbit in an iterative process guided by pre-launch testing. This paper discusses the planned tests to be performed on GLM over the six-month Post Launch Test period to optimize and demonstrate GLM performance.

  2. Post launch calibration and testing of the Advanced Baseline Imager on the GOES-R satellite

    Science.gov (United States)

    Lebair, William; Rollins, C.; Kline, John; Todirita, M.; Kronenwetter, J.

    2016-05-01

    The Geostationary Operational Environmental Satellite R (GOES-R) series is the planned next generation of operational weather satellites for the United State's National Oceanic and Atmospheric Administration. The first launch of the GOES-R series is planned for October 2016. The GOES-R series satellites and instruments are being developed by the National Aeronautics and Space Administration (NASA). One of the key instruments on the GOES-R series is the Advance Baseline Imager (ABI). The ABI is a multi-channel, visible through infrared, passive imaging radiometer. The ABI will provide moderate spatial and spectral resolution at high temporal and radiometric resolution to accurately monitor rapidly changing weather. Initial on-orbit calibration and performance characterization is crucial to establishing baseline used to maintain performance throughout mission life. A series of tests has been planned to establish the post launch performance and establish the parameters needed to process the data in the Ground Processing Algorithm. The large number of detectors for each channel required to provide the needed temporal coverage presents unique challenges for accurately calibrating ABI and minimizing striping. This paper discusses the planned tests to be performed on ABI over the six-month Post Launch Test period and the expected performance as it relates to ground tests.

  3. Post-Launch Calibration and Testing of Space Weather Instruments on GOES-R Satellite

    Science.gov (United States)

    Tadikonda, Sivakumara S. K.; Merrow, Cynthia S.; Kronenwetter, Jeffrey A.; Comeyne, Gustave J.; Flanagan, Daniel G.; Todirita, Monica

    2016-01-01

    The Geostationary Operational Environmental Satellite - R (GOES-R) is the first of a series of satellites to be launched, with the first launch scheduled for October 2016. The three instruments - Solar Ultra Violet Imager (SUVI), Extreme ultraviolet and X-ray Irradiance Sensor (EXIS), and Space Environment In-Situ Suite (SEISS) provide the data needed as inputs for the product updates National Oceanic and Atmospheric Administration (NOAA) provides to the public. SUVI is a full-disk extreme ultraviolet imager enabling Active Region characterization, filament eruption, and flare detection. EXIS provides inputs to solar backgrounds/events impacting climate models. SEISS provides particle measurements over a wide energy-and-flux range that varies by several orders of magnitude and these data enable updates to spacecraft charge models for electrostatic discharge. EXIS and SEISS have been tested and calibrated end-to-end in ground test facilities around the United States. Due to the complexity of the SUVI design, data from component tests were used in a model to predict on-orbit performance. The ground tests and model updates provided inputs for designing the on-orbit calibration tests. A series of such tests have been planned for the Post-Launch Testing (PLT) of each of these instruments, and specific parameters have been identified that will be updated in the Ground Processing Algorithms, on-orbit parameter tables, or both. Some of SUVI and EXIS calibrations require slewing them off the Sun, while no such maneuvers are needed for SEISS. After a six-month PLT period the GOES-R is expected to be operational. The calibration details are presented in this paper.

  4. Post-Launch Calibration and Testing of Space Weather Instruments on GOES-R Satellite

    Science.gov (United States)

    Tadikonda, S. K.; Merrow, Cynthia S.; Kronenwetter, Jeffrey A.; Comeyne, Gustave J.; Flanagan, Daniel G.; Todrita, Monica

    2016-01-01

    The Geostationary Operational Environmental Satellite - R (GOES-R) is the first of a series of satellites to be launched, with the first launch scheduled for October 2016. The three instruments Solar UltraViolet Imager (SUVI), Extreme ultraviolet and X-ray Irradiance Sensor (EXIS), and Space Environment In-Situ Suite (SEISS) provide the data needed as inputs for the product updates National Oceanic and Atmospheric Administration (NOAA) provides to the public. SUVI is a full-disk extreme ultraviolet imager enabling Active Region characterization, filament eruption, and flare detection. EXIS provides inputs to solar back-ground-sevents impacting climate models. SEISS provides particle measurements over a wide energy-and-flux range that varies by several orders of magnitude and these data enable updates to spacecraft charge models for electrostatic discharge. EXIS and SEISS have been tested and calibrated end-to-end in ground test facilities around the United States. Due to the complexity of the SUVI design, data from component tests were used in a model to predict on-orbit performance. The ground tests and model updates provided inputs for designing the on-orbit calibration tests. A series of such tests have been planned for the Post-Launch Testing (PLT) of each of these instruments, and specific parameters have been identified that will be updated in the Ground Processing Algorithms, on-orbit parameter tables, or both. Some of SUVI and EXIS calibrations require slewing them off the Sun, while no such maneuvers are needed for SEISS. After a six-month PLT period the GOES-R is expected to be operational. The calibration details are presented in this paper.

  5. Post-launch calibration and testing of space weather instruments on GOES-R satellite

    Science.gov (United States)

    Tadikonda, Sivakumara S. K.; Merrow, Cynthia S.; Kronenwetter, Jeffrey A.; Comeyne, Gustave J.; Flanagan, Daniel G.; Todirita, Monica

    2016-05-01

    The Geostationary Operational Environmental Satellite - R (GOES-R) is the first of a series of satellites to be launched, with the first launch scheduled for October 2016. The three instruments -- Solar UltraViolet Imager (SUVI), Extreme ultraviolet and X-ray Irradiance Sensor (EXIS), and Space Environment In-Situ Suite (SEISS) provide the data needed as inputs for the product updates National Oceanic and Atmospheric Administration (NOAA) provides to the public. SUVI is a full-disk extreme ultraviolet imager enabling Active Region characterization, filament eruption, and flare detection. EXIS provides inputs to solar backgrounds/events impacting climate models. SEISS provides particle measurements over a wide energy-and-flux range that varies by several orders of magnitude and these data enable updates to spacecraft charge models for electrostatic discharge. EXIS and SEISS have been tested and calibrated end-to-end in ground test facilities around the United States. Due to the complexity of the SUVI design, data from component tests were used in a model to predict on-orbit performance. The ground tests and model updates provided inputs for designing the on-orbit calibration tests. A series of such tests have been planned for the Post-Launch Testing (PLT) of each of these instruments, and specific parameters have been identified that will be updated in the Ground Processing Algorithms, on-orbit parameter tables, or both. Some of SUVI and EXIS calibrations require slewing them off the Sun, while no such maneuvers are needed for SEISS. After a six-month PLT period the GOES-R is expected to be operational. The calibration details are presented in this paper.

  6. SMAP Post-launch Field Campaign Planning

    Science.gov (United States)

    The SMAP post-launch Cal/Val activities are intended both to assess the quality of the mission products and to support analyses that lead to their improvement. A suite of complementary methodologies will be employed that will result in a robust global assessment. Much of the work will occur in the C...

  7. STS-114: Post Launch Press Conference

    Science.gov (United States)

    2005-01-01

    Dean Acosta, Deputy Assistant Administrator for Public Affairs hosted this post launch press conference. Present were Mike Griffin, NASA Administrator; William Ready, Associate Administrator for Space Operations; Bill Parsons, Space Shuttle Program Manager; Mike Leinbach, NASA Launch Director; and Wayne Hill, Deputy Program Manager for Space Shuttle Program. Each expressed thanks to all of NASA Officials and employees, contractors, vendors and the crew for their hard work the past two and a half years that resulted the successful and pristine launch of Space Shuttle Discovery. The Panel emphasized that through extensive technical analysis, thorough planning and tremendous amount of public support brought them full circle again to return to flight. Flight safety, debris during rocket separation, sensors, observations from the mission control, launch conditions were some of the topics discussed with the News media.

  8. STS-114: Post Launch MMT Briefing

    Science.gov (United States)

    2005-01-01

    Bill Parsons, Space Shuttle Program Manager, and Wayne Hill, Deputy Manager of the Space Shuttle Program, and Chair of the Mission Management Team talks about the flight day 2 of the Discovery. Bill noted that flight operations are extremely going on well. He also explained an unexpected debris event on a power ramp little ways down where LH2 ramp begins. Before flight and based from technical data, slight modifications were done on the power ramp to ensure safety of return to flight. Bill also noted that STS-114 is a test flight; all data collected and brought back by the crew will be analyzed to ensure that all information needed is sufficient to work on faults and defects and to make appropriate repairs. Wayne discussed on flight safety. He emphasized the need to thoroughly inspect the thermal protection system of the Orbiter to ensure safe entry. Inspection of still photographs from the ISS and the boom sensor system scan are the primary means to understand engineering data in terms of the immediate flight safety. He also reported accomplishments for the day such as survey of the Orbiter boom system, all the wing leading edge, RCC panels and the nose cap, to make sure these are in good shape and working well, and re-emphasized that these are primary methods to clear the thermal protection system of the Orbiter to prove that it is safe to come home on this flight.

  9. Prime candidate earth targets for the post-launch radiometric calibration of space-based optical imaging instruments

    Science.gov (United States)

    Teillet, P.M.; Barsi, J.A.; Chander, G.; Thome, K.J.

    2007-01-01

    This paper provides a comprehensive list of prime candidate terrestrial targets for consideration as benchmark sites for the post-launch radiometric calibration of space-based instruments. The key characteristics of suitable sites are outlined primarily with respect to selection criteria, spatial uniformity, and temporal stability. The establishment and utilization of such benchmark sites is considered an important element of the radiometric traceability of satellite image data products for use in the accurate monitoring of environmental change.

  10. The Archimedes satellite system

    Science.gov (United States)

    Taylor, Stuart C.; Shurvinton, William D.

    1992-03-01

    Archimedes is a satellite system conceived by the European Space Agency (ESA) to effectively serve the European market for Mobile Radio Services (MRS). This paper describes the requirements and technical design of the Archimedes satellite system. The underlying assumptions and trade-offs behind the design are detailed and the design is compared and contrasted against alternative design solutions, both technically and economically. A path forward for the development of the system is indicated.

  11. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

    @@ China's meteorological satellite program consists of five systems,namely the satellite system,the launch vehicle system,the launch center system,TT&C and the ground application system.The satellite system consists of FengYun (FY) polar orbiting series and FY geostationary series,which are launched by LM launch vehicles from Taiyan Satellite Launch Center (TSLC) and Xichang Satellite Launch Center (XSLC) respectively.

  12. Pre- and Post-Launch Spatial Quality of the Landsat 8 Thermal Infrared Sensor

    Directory of Open Access Journals (Sweden)

    Brian N. Wenny

    2015-02-01

    Full Text Available The Thermal Infrared Sensor (TIRS for the Landsat 8 platform was designed and built at NASA Goddard Space Flight Center (GSFC. TIRS data will extend the data record for thermal observations from the heritage Landsat sensors, dating back to the launch of Landsat 4 in 1982. The two-band (10.9 and 12.0 μm pushbroom sensor with a 185 km-wide swath uses a staggered arrangement of quantum well infrared photodetector (QWIPs arrays. The required spatial resolution is 100 m for TIRS, with the assessment of crop moisture and water resources being science drivers for that resolution. The evaluation of spatial resolution typically relies on a straight knife-edge technique to determine the spatial edge response of a detector system, and such an approach was implemented for TIRS. Flexibility in the ground calibration equipment used for TIRS thermal-vacuum chamber testing also made possible an alternate strategy that implemented a circular target moved in precise sub-pixel increments across the detectors to derive the edge response. On-orbit, coastline targets were developed to evaluate the spatial response performance. Multiple targets were identified that produced similar results to one another. Even though there may be a slight bias in the point spread function (PSF/modulation transfer function (MTF estimates towards poorer performance using this approach, it does have the ability to track relative changes for monitoring long-term instrument status. The results for both pre- and post-launch response analysis show general good agreement and consistency with edge slope along-track values of 0.53 and 0.58 pre- and post-launch and across-track values 0f 0.59 and 0.55 pre- and post-launch.

  13. Inter-comparison of NPP/CrIS radiances with VIIRS, AIRS, and IASI: a post-launch calibration assessment

    Science.gov (United States)

    Wang, Likun; Han, Yong; Tremblay, Denis; Weng, Fuzhong; Goldberg, Mitchell

    2012-11-01

    The Cross-track Infrared Sounder (CrIS) on the newly-launched Suomi National Polar-orbiting Partnership (Suomi NPP) is a Fourier transform spectrometer that provides soundings of the atmosphere with 1305 spectral channels, over 3 wavelength ranges: LWIR (9.14 - 15.38 μm) MWIR (5.71 - 8.26 μm) and SWIR (3.92 - 4.64 μm). An accurate spectral and radiometric calibration as well as geolocation is fundamental for CrIS radiance Sensor Data Records (SDRs). In this study, through inter- and intra-satellite calibration efforts, we focus on assessment of NPP/CrIS post-launch performance. First, we compare CrIS hyperspectral radiance measurements with the Atmospheric Infrared Sounder (AIRS) on NASA Earth Observing System (EOS) Aqua and Infrared Atmospheric Sounding Interferometer (IASI) on Metop-A to examine spectral and radiometric consistence and difference among three hyperspectral IR sounders. Secondly, an accurate collocation algorithm has been developed to collocate high spatial resolution measurements from the Visible Infrared Imager Radiometer Suite (VIIRS) within each CrIS Field of View (FOV). We compare CrIS spectrally-averaged radiances with the spatially-averaged and collocated pixels from the VIIRS IR channels. Since CrIS and VIIRS are onboard on the same satellite platform, the intra-satellite comparison will allow examining the radiometric difference between CrIS and VIIRS with scene temperatures, scan angles, and orbital position. In addition, given a high spatial resolution of VIIRS channels, the VIIRS-CrIS comparison results can access geolocation accuracy of CrIS that have relatively large FOVs (14 km at ndair) using high resolution VIIRS pixel (375m or 750m at nadir).

  14. Post Launch Monitoring of food products: what can be learned from pharmacovigilance.

    Science.gov (United States)

    van Puijenbroek, E P; Hepburn, P A; Herd, T M; van Grootheest, A C

    2007-03-01

    Post Launch Monitoring (PLM) is one of the new approaches that are used in assessing the safety of novel foods or ingredients. It shares a close resemblance with procedures applied in the field of medicines, where Post Marketing Surveillance (PMS) has been carried out since the beginning of the 1960s. For this reason, Unilever and the Netherlands Pharmacovigilance Centre Lareb, maintaining the national reporting scheme in the Netherlands for adverse drug reactions, have been working together to optimize the Unilever's Post Launch Monitoring service. As a result of this cooperation a practical model for conducting PLM for food products has been developed. This model is also applicable for consumer products in general. The system allows for coding and assessing reports and the early detection of 'signals' of unintended health reactions. The methodological issues surrounding reporting of possible health reactions and practical issues surrounding coding and assessment of the reports that were encountered in the first period of this partnership are discussed. In addition, similarities and differences concerning PMS and PLM are described.

  15. Integrated Satellite-HAP Systems

    DEFF Research Database (Denmark)

    Cianca, Ernestina; De Sanctis, Mauro; De Luise, Aldo

    2005-01-01

    for an efficient hybrid terrestrial-satellite communication system. Two integrated HAP-satellite scenarios are presented, in which the HAP is used to overcome some of the shortcomings of satellite- based communications. Moreover, it is shown that the integration of HAPs with satellite systems can be used......Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element...

  16. Cooperative and cognitive satellite systems

    CERN Document Server

    Chatzinotas, Symeon; De Gaudenzi, Riccardo

    2015-01-01

    Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

  17. Meteorological satellite systems

    CERN Document Server

    Tan, Su-Yin

    2014-01-01

    “Meteorological Satellite Systems” is a primer on weather satellites and their Earth applications. This book reviews historic developments and recent technological advancements in GEO and polar orbiting meteorological satellites. It explores the evolution of these remote sensing technologies and their capabilities to monitor short- and long-term changes in weather patterns in response to climate change. Satellites developed by various countries, such as U.S. meteorological satellites, EUMETSAT, and Russian, Chinese, Japanese and Indian satellite platforms are reviewed. This book also discusses international efforts to coordinate meteorological remote sensing data collection and sharing. This title provides a ready and quick reference for information about meteorological satellites. It serves as a useful tool for a broad audience that includes students, academics, private consultants, engineers, scientists, and teachers.

  18. The Radiometer Atmospheric Cubesat Experiment Post-Launch Results

    Science.gov (United States)

    Lim, B.; Misra, S.

    2015-12-01

    The Jet Propulsion Laboratory (JPL) developed the Radiometer Atmospheric CubeSat Experiment (RACE) that was lost during the Orbital 3 (Orb-3) launch anomaly on October 28, 2014. The 3U CubeSat mission would have measured 2 channels of the 183 GHz water vapor line and raised the technology readiness level (TRL) of various subsystems to 6. Despite the launch failure, several hundreds of hours of instrument operation data was taken, including measurements in thermal vacuum of the complete spacecraft system. These data is used to evaluate the 35 nm Indium Phosphide (InP) receivers, and the low noise amplifier (LNA) based internal calibration system. The thermal vacuum measurements included frequent observations of a 'cold' and 'hot' target allowing for various receiver parameters to be calculated. The payload thermal vacuum data show that the receiver front ends performed as expected in terms of the gain (>35 dB) and drift (0.06 dB/K). The data also shows that integration could be performed with decreasing noise up to ~30 seconds, allowing for the system to be calibrated within that time period. The expected spacecraft calibration period would have been every 12 seconds. The injected noise from the load terminated LNA show magnitudes from 50 - 150 K that can be tuned which would meet most requirements. However the temperature coefficient is large at ~3 K/K which is over an order of magnitude larger than typical noise diodes. For nanosatellite class spacecraft, the power required to properly maintain the physical temperature range (±0.1K) would be challenging. On larger spacecraft, this methodology may still be viable, depending on the availability of suitable noise diodes at 183 GHz. While the CubeSat did not take measurements in space, the ground data in the relevant environment and extensive testing allows us to raise the following subsystems to TRL 6: 1) 183 GHz 35 nm InP receiver, 2) 183 GHz direct detect receiver and 3) 183 GHz LNA based calibration system.

  19. Spanish Earth Observation Satellite System

    Science.gov (United States)

    Borges, A.; Cerezo, F.; Fernandez, M.; Lomba, J.; Lopez, M.; Moreno, J.; Neira, A.; Quintana, C.; Torres, J.; Trigo, R.; Urena, J.; Vega, E.; Vez, E.

    2010-12-01

    The Spanish Ministry of Industry, Tourism and Trade (MITyC) and the Ministry of Defense (MoD) signed an agreement in 2007 for the development of a "Spanish Earth Observation Satellite System" based, in first instance, on two satellites: a high resolution optical satellite, called SEOSAT/Ingenio, and a radar satellite based on SAR technology, called SEOSAR/Paz. SEOSAT/Ingenio is managed by MITyC through the Centre for the Development of Industrial Technology (CDTI), with technical and contractual support from the European Space Agency (ESA). HISDESA T together with the Spanish Instituto Nacional de Técnica Aeroespacial (INTA, National Institute for Aerospace Technology) will be responsible for the in-orbit operation and the commercial operation of both satellites, and for the technical management of SEOSAR/Paz on behalf of the MoD. In both cases EADS CASA Espacio (ECE) is the prime contractor leading the industrial consortia. The ground segment development will be assigned to a Spanish consortium. This system is the most important contribution of Spain to the European Programme Global Monitoring for Environment and Security, GMES. This paper presents the Spanish Earth Observation Satellite System focusing on SEOSA T/Ingenio Programme and with special emphasis in the potential contribution to the ESA Third Party Missions Programme and to the Global Monitoring for Environment and Security initiative (GMES) Data Access.

  20. 14 CFR 417.415 - Post-launch and post-flight-attempt hazard controls.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Post-launch and post-flight-attempt hazard controls. 417.415 Section 417.415 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION...-flight-attempt hazard controls. (a) A launch operator must establish, maintain and perform procedures...

  1. Post Launch Monitoring of food products : what can be learned from pharmacovigilance

    NARCIS (Netherlands)

    van Puijenbroek, E P; Hepburn, P A; Herd, T M; van Grootheest, A C

    2007-01-01

    Post Launch Monitoring (PLM) is one of the new approaches that are used in assessing the safety of novel foods or ingredients. It shares a close resemblance with procedures applied in the field of medicines, where Post Marketing Surveillance (PMS) has been carried out since the beginning of the 1960

  2. Post Launch Monitoring of food products : what can be learned from pharmacovigilance

    NARCIS (Netherlands)

    van Puijenbroek, E P; Hepburn, P A; Herd, T M; van Grootheest, A C

    2007-01-01

    Post Launch Monitoring (PLM) is one of the new approaches that are used in assessing the safety of novel foods or ingredients. It shares a close resemblance with procedures applied in the field of medicines, where Post Marketing Surveillance (PMS) has been carried out since the beginning of the 1960

  3. Advanced satellite communication system

    Science.gov (United States)

    Staples, Edward J.; Lie, Sen

    1992-01-01

    The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

  4. An Overview of the Joint Polar Satellite System (JPSS Science Data Product Calibration and Validation

    Directory of Open Access Journals (Sweden)

    Lihang Zhou

    2016-02-01

    Full Text Available The Joint Polar Satellite System (JPSS will launch its first JPSS-1 satellite in early 2017. The JPSS-1 and follow-on satellites will carry aboard an array of instruments including the Visible Infrared Imaging Radiometer Suite (VIIRS, the Cross-track Infrared Sounder (CrIS, the Advanced Technology Microwave Sounder (ATMS, and the Ozone Mapping and Profiler Suite (OMPS. These instruments are similar to the instruments currently operating on the Suomi National Polar-orbiting Partnership (S-NPP satellite. In preparation for the JPSS-1 launch, the JPSS program at the Center for Satellite Applications and Research (JSTAR Calibration/Validation (Cal/Val teams, have laid out the Cal/Val plans to oversee JPSS-1 science products’ algorithm development efforts, verification and characterization of these algorithms during the pre-launch period, calibration and validation of the products during post-launch, and long-term science maintenance (LTSM. In addition, the team has developed the necessary schedules, deliverables and infrastructure for routing JPSS-1 science product algorithms for operational implementation. This paper presents an overview of these efforts. In addition, this paper will provide insight into the processes of both adapting S-NPP science products for JPSS-1 and performing upgrades for enterprise solutions, and will discuss Cal/Val processes and quality assurance procedures.

  5. The Omninet mobile satellite system

    Science.gov (United States)

    Salmasi, A.; Curry, W.

    Mobile Satellite System (MSS) design offering relatively low cost voice, data, and position location services to nonmetropolitan areas of North America is proposed. The system provides spectrally efficient multiple access and modulation techniques, and flexible user interconnection to public and private switched networks. Separate UHF and L-band satellites employing two 9.1 m unfurlable antennas each, achieve a 6048 channel capacity and utilize spot beams. Mobile terminals have modular design and employ 5 dBi omnidirectional antennas. Gateway stations (with two 5 m Ku-band antennas) and base stations (with a single 1.8 m Ku-band antenna) transmit terrestrial traffic to the satellite, where traffic is then transponded via an L-band or UHF downlink to mobile users. The Network Management Center uses two 5-m antennas and incorporates the Integrated-Adaptive Mobile Access Protocol to assure demand assignment of satellite capacity. Preliminary implementation of this low-risk system involves a mobile alphanumeric data service employing receive-only terminals at Ku-band projected for 1987, and plans for the launching of L-band receive-only packages as early as 1988.

  6. Satellite Attitude Control System Simulator

    Directory of Open Access Journals (Sweden)

    G.T. Conti

    2008-01-01

    Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

  7. Economics of satellite communications systems

    Science.gov (United States)

    Pritchard, Wilbur L.

    This paper is partly a tutorial, telling systematically how one goes about calculating the total annual costs of a satellite communications system, and partly the expression of some original ideas on the choice of parameters so as to minimize these costs. The calculation of costs can be divided into two broad categories. The first is technical and is concerned with estimating what particular equipment will cost and what will be the annual expense to maintain and operate it. One starts in the estimation of any new system by listing the principal items of equipment, such as satellites, earth stations of various sizes and functions, telemetry and tracking equipment and terrestrial interfaces, and then estimating how much each item will cost. Methods are presented for generating such estimates, based on a knowledge of the gross parameters, such as antenna size, coverage area, transmitter power and information rate. These parameters determine the system performance and it is usually possible, knowing them, to estimate the costs of the equipment rather well. Some formulae based on regression analyses are presented. Methods are then given for estimating closely related expenses, such as maintenance and operation, and then an approximate method is developed for estimating terrestrial interconnection costs. It is pointed out that in specific cases when tariff and geographical information are available, it is usually better to work with specific data, but nonetheless it is often desirable, especially in global system estimating, to approximate these interconnect costs without recourse to individual tariffs. The procedure results in a set of costs for the purchase of equipment and its maintenance, and a schedule of payments. Some payments will be incurred during the manufacture of the satellite and before any systems operation, but many will not be incurred until the system is no longer in use, e.g. incentives. In any case, with the methods presented in the first section, one

  8. Post-Launch Calibration Support for VIIRS Onboard NASA NPP Spacecraft

    Science.gov (United States)

    Xiong, Xiaoxion; Chiang, Kwo-Fu; McIntire, Jeffrey; Schwaller, Matthew; Butler, James

    2011-01-01

    The NPP Instrument Calibration Support Element (NICSE) is one of the elements within the NASA NPP Science Data Segment (SDS). The primary responsibility of NICSE is to independently monitor and evaluate on-orbit radiometric and geometric performance of the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument and to validate its Sensor Data Record (SDR) [1]. The NICSE interacts and works closely with other SDS Product Evaluation and Analysis Tools Elements (PEATE) and the NPP Science Team (ST) and supports their on-orbit data product calibration and validation efforts. The NICSE also works closely with the NPP Instrument Calibration Support Team (NICST) during sensor pre-launch testing in ambient and thermal vacuum environment [2]. This paper provides an overview of NICSE VIIRS sensor post-launch calibration support with a focus on the use of sensor on-board calibrators (OBC) for the radiometric calibration and characterization. It presents the current status of NICSE post-launch radiometric calibration tool development effort based on its design requirements

  9. Metop-BAVHRR IR channel post-launch calibration and verification tests

    Science.gov (United States)

    Chang, Tiejun; Wu, Xiangqian; Weng, Fuzhong

    2013-09-01

    Meteorological Operational (METOP)-B spacecraft was launched on September 17, 2012, and the Advanced Very High Resolution Radiometer (AVHRR) IR channels were activated October 18. AVHRR instrument has been tested and characterized pre-launch under thermal vacuum (TV) condition by the instrument vender. The instrument dynamic range, noise equivalent differential temperature (NEDT), and nonlinear response have been characterized in the test. Basing on the TV test data, the calibration coefficients are generated for post-launch. The on-orbit verification tests have been performed to verify the instrument response and performance, including the dynamic range, NEDT, on-board blackbody (BB) temperature, instrument response calibration, and instrument status from the telemetry data. The post-launch Cal/Val test is to improve the calibration accuracy and enhance the L1B data quality. These tests include stray light analysis, instrument gain verification, and uncertainty assessment. The stray light impact on the calibration is estimated as 0.2% for 11 μm channel, 0.3% for 12 μm channel, and 3% for 3.7μm channel. The inter-comparison AVHRR IR channel radiances with the radiance derived from Infrared Atmospheric Sounding Interferometer (IASI) measurement has been performed and the AVHRR bias shoes brightness temperature dependency.

  10. POST-LAUNCHING MONITORING ACTIVITIES FOR NEW TRANSACTIONAL BANKING PRODUCTS ADDRESSED TO SMES (CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    Giuca Simona-Mihaela

    2014-07-01

    Full Text Available The current paper has the aim to provide guidelines for post-launching monitoring activities and steps related to new transactional banking products addressed to SMEs. While the pre-launching activities have the purpose of accurately defining the objectives, assumptions and estimations, the purpose of the post-launching plan is to identify: if the final objectives of a product launching have been met, on one hand, to analyze results in the sense of identifying an efficient action plan in order to overcome the lack of results (if case, but most important, to identify opportunities for optimizing the products and for communicating properly the value proposition. This paper also presents schemes for monitoring the results from a business case and for motivating the sales force, as an essential step in increasing the sales. Therefore, alternatives of incentive campaigns are presented, as sustainable campaigns with to purpose to achieve an expected success rate. As an additional support guideline for the sales force, some scenarios and post-sales actions are presented, together with an example of portfolio analysis considering potential per client. Considering the methods and details presented in the current paper, one can identify the importance and find out how to monitor the results after launching a new transactional product addressed to SMEs, can understand and design an incentive scheme and also define actions to be taken in order to increase revenues from a newly launched transactional product.

  11. Global navigation satellite systems and their applications

    CERN Document Server

    Madry, Scott

    2015-01-01

    Dr. Madry, one of the world's leading experts in the field, provides in a condensed form a quick yet comprehensive overview of satellite navigation. This book concisely addresses the latest technology, the applications, the regulatory issues, and the strategic implications of satellite navigation systems. This assesses the strengths and weaknesses of satellite navigation networks and review of all the various national systems now being deployed and the motivation behind the proliferation of these systems.

  12. Integration of mobile satellite and cellular systems

    Science.gov (United States)

    Drucker, Elliott H.; Estabrook, Polly; Pinck, Deborah; Ekroot, Laura

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established. Users equipped for both cellular and satellite service can take advantage of a number of features made possible by such integration, including seamless handoff and universal roaming. To provide maximum benefit at lowest posible cost, the means by which these systems are integrated must be carefully considered. Mobile satellite hub stations must be configured to efficiently interface with cellular Mobile Telephone Switching Offices (MTSO's), and cost effective mobile units that provide both cellular and satellite capability must be developed.

  13. IMPLEMENTATION OF AERONAUTICAL LOCAL SATELLITE AUGMENTATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Stojce Ilcev

    2011-03-01

    Full Text Available Abstract. This paper introduces development and implementation of new Local Satellite AugmentationSystem as an integration component of the Regional Satellite Augmentation System (RSAS employingcurrent and new Satellite Communications, Navigation and Surveillance (CNS for improvement of the AirTraffic Control (ATC and Air Traffic Management (ATM and for enhancement safety systems includingtransport security and control of flights in all stages, airport approaching, landing, departures and allmovements over airport surface areas. The current first generation of the Global Navigation Satellite SystemGNSS-1 applications are represented by fundamental military solutions for Position, Velocity and Time ofthe satellite navigation and determination systems such as the US GPS and Russian GLONASS (Former-USSR requirements, respectively. The establishment of Aeronautical CNS is also discussed as a part ofGlobal Satellite Augmentation Systems of GPS and GLONASS systems integrated with existing and futureRSAS and LSAS in airports areas. Specific influence and factors related to the Comparison of the Currentand New Aeronautical CNS System including the Integration of RSAS and GNSS solutions are discussedand packet of facts is determined to maximize the new satellite Automatic Dependent Surveillance System(ADSS and Special Effects of the RSAS Networks. The possible future integration of RSAS and GNSS andthe common proposal of the satellite Surface Movement Guidance and Control are presented in thechangeless ways as of importance for future enfacements of ATC and ATM for any hypothetical airportinfrastructure.Keywords: ADSS, ATC, ATM, CNS, GSAS, LRAS, RSAS, SMGC, Special Effects of RSAS.

  14. Design of the American Mobile Satellite System

    Science.gov (United States)

    Kittiver, Charles

    1991-01-01

    This paper presents an overview of the American Mobile Satellite Corporation (AMSC) Mobile Satellite System (MSS). A summary of the mobile satellite (MSAT) design and overall performance is provided. The design and components of both the forward link and return link transponders are described in detail. The design and operation of a unique hybrid matrix amplifier that offers flexible power distribution is outlined. The conceptual design and performance of three types of land mobile antennas are described.

  15. Integration of Mobil Satellite and Cellular Systems

    Science.gov (United States)

    Drucker, E. H.; Estabrook, P.; Pinck, D.; Ekroot, L.

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established.

  16. Experimental millimeter-wave satellite communications system

    Science.gov (United States)

    Suzuki, Yoshiaki; Shimada, Masaaki; Arimoto, Yoshinori; Shiomi, Tadashi; Kitazume, Susumu

    This paper describes an experimental system of millimeter-wave satellite communications via Japan's Engineering Test Satellite-VI (ETS-VI) and a plan of experiments. Two experimental missions are planned using ETS-VI millimeter-wave (43/38 GHz bands) transponder, considering the millimeter-wave characteristics such as large transmission capacity and possibility to construct a small earth station with a high gain antenna. They are a personal communication system and an inter-satellite communication system. Experimental system including the configuration and the fundamental functions of the onboard transponder and the outline of the experiments are presented.

  17. Satellite Sanitary Systems in Kampala, Uganda

    NARCIS (Netherlands)

    Letema, S.; Van Vliet, B.; Van Lier, J.B.

    2011-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas, e

  18. Satellite Sanitary Systems in Kampala, Uganda

    NARCIS (Netherlands)

    Letema, S.C.; Vliet, van B.J.M.; Lier, van J.B.

    2012-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas, e

  19. CryoSat-2: Post launch performance of SIRAL-2 and its calibration/validation

    Science.gov (United States)

    Cullen, Robert; Francis, Richard; Davidson, Malcolm; Wingham, Duncan

    2010-05-01

    1. INTRODUCTION The main payload of CryoSat-2 [1], SIRAL (Synthetic interferometric radar altimeter), is a Ku band pulse-width limited radar altimeter which transmits pulses at a high pulse repetition frequency thus making received echoes phase coherent and suitable for azimuth processing [2]. The azimuth processing in conjunction with correction for slant range improves along track resolution to about 250 meters which is a significant improvement over traditional pulse-width limited systems such as Envisat RA-2, [3]. CryoSat-2 will be launched on 25th February 2010 and this paper describes the pre and post launch measures of CryoSat/SIRAL performance and the status of mission validation planning. 2. SIRAL PERFORMANCE: INTERNAL AND EXTERNAL CALIBRATION Phase coherent pulse-width limited radar altimeters such as SIRAL-2 pose a new challenge when considering a strategy for calibration. Along with the need to generate the well understood corrections for transfer function amplitude with respect to frequency, gain and instrument path delay there is also a need to provide corrections for transfer function phase with respect to frequency and AGC setting, phase variation across bursts of pulses. Furthermore, since some components of these radars are temperature sensitive one needs to be careful when the deciding how often calibrations are performed whilst not impacting mission performance. Several internal calibration ground processors have been developed to model imperfections within the CryoSat-2 radar altimeter (SIRAL-2) hardware and reduce their effect from the science data stream via the use of calibration correction auxiliary products within the ground segment. We present the methods and results used to model and remove imperfections and describe the baseline for usage of SIRAL-2 calibration modes during the commissioning phase and the operational exploitation phases of the mission. Additionally we present early results derived from external calibration of SIRAL via

  20. Advanced tracking and data relay satellite system

    Science.gov (United States)

    Stern, Daniel

    1992-01-01

    The purpose of this communication satellite system are as follows: to provide NASA needs for satellite tracking and communications through the year 2012; to maintain and augment the current TDRS system when available satellite resources are expended in the latter part of the decade; to provide the necessary ground upgrade to support the augmented services; and to introduce new technology to reduce the system life cycle cost. It is concluded that no ATDRS spacecraft requirement for new modulation techniques, that data rate of 650 MBps is required, and that Space Station Freedom requirement is for 650 MBps data some time after the year 2000.

  1. Reliability Growth Analysis of Satellite Systems

    Science.gov (United States)

    2012-09-01

    obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that of a...parameters are obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that...System Figures 7a through 7i display the real CIF for a variety of GOES missions. These cumulative intensity functions have shapes similar to the

  2. A new digital land mobile satellite system

    Science.gov (United States)

    Schneider, Philip

    A description is given of the different digital services planned to be carried over existing and planned mobile satellite systems. These systems are then compared with analog services in terms of bandwidth and power efficiency. This comparison provides the rationale for the establishment of a digital land mobile satellite service (DLMSS) to use frequencies that are currently available but not yet assigned to a domestic mobile satellite system in the United States. The focus here is on the expected advantages of digital transmission techniques in accommodating additional mobile satellite systems in this portion of the spectrum, and how such techniques can fully satisfy voice, data and facsimile mobile communications requirements in a cost effective manner. A description is given of the system architecture of the DMLSS service proposed by the Geostar Messaging Corporation (GMC) and the market potential of DLMSS.

  3. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

    @@ (Continued) Applications In Global Environment And Natural Disaster Monitoring 1) Application in world crop yield estimation China is now one of the few nations in the world that can provide operational service with both GEO and polar-orbit meteorological satellites.

  4. Alignments between galaxies, satellite systems and haloes

    CERN Document Server

    Shao, Shi; Frenk, Carlos S; Gao, Liang; Crain, Robert A; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    The spatial distribution of the satellite populations of the Milky Way and Andromeda are puzzling in that they are nearly perpendicular to the disks of their central galaxies. To understand the origin of such configurations we study the alignment of the central galaxy, satellite system and dark matter halo in the largest of the "Evolution and Assembly of GaLaxies and their Environments" (EAGLE) simulation. We find that centrals and their satellite systems tend to be well aligned with their haloes, with a median misalignment angle of $33^{\\circ}$ in both cases. While the centrals are better aligned with the inner $10$ kpc halo, the satellite systems are better aligned with the entire halo indicating that satellites preferentially trace the outer halo. The central - satellite alignment is weak (median misalignment angle of $52^{\\circ}$) and we find that around $20\\%$ of systems have a misalignment angle larger than $78^{\\circ}$, which is the value for the Milky Way. The central - satellite alignment is a conseq...

  5. Satellite power system (SPS) initial insurance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-09-01

    The beginning of a process to educate the insurance industry about the Satellite Power System is reported. The report is divided into three sections. In the first section a general history describes how space risks are being insured today. This is followed by an attempt to identify the major risks inherent to the SPS. The final section presents a general projection of insurance market reactions to the Satellite Power System.

  6. Satellite Application for Disaster Management Information Systems

    Science.gov (United States)

    Okpanachi, George

    Abstract Satellites are becoming increasingly vital to modern day disaster management activities. Earth observation (EO) satellites provide images at various wavelengths that assist rapid-mapping in all phases of the disaster management cycle: mitigation of potential risks in a given area, preparedness for eventual disasters, immediate response to a disaster event, and the recovery/reconstruction efforts follo wing it. Global navigation satellite systems (GNSS) such as the Global Positioning System (GPS) assist all the phases by providing precise location and navigation data, helping manage land and infrastructures, and aiding rescue crews coordinate their search efforts. Effective disaster management is a complex problem, because it involves many parameters, which are usually not easy to measure and even identify: Analysis of current situation, planning, optimum resource management, coordination, controlling and monitoring current activities and making quick and correct decisions are only some of these parameters, whose complete list is very long. Disaster management information systems (DMIS) assist disaster management to analyse the situation better, make decisions and suggest further actions following the emergency plans. This requires not only fast and thorough processing and optimization abilities, but also real-time data provided to the DMIS. The need of DMIS for disaster’s real-time data can be satisfied by small satellites data utilization. Small satellites can provide up-to-data, plus a better media to transfer data. This paper suggests a rationale and a framework for utilization of small Satellite data by DMIS. DMIS should be used ‘’before’’, ‘’during’’ and ‘’after’’ the disasters. Data provided by the Small Satellites are almost crucial in any period of the disasters, because early warning can save lives, and satellite data may help to identify disasters before they occur. The paper also presents’ ‘when’’,

  7. Odyssey, an optimized personal communications satellite system

    Science.gov (United States)

    Rusch, Roger J.

    Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55° to the equatorial plane

  8. A Space Based Solar Power Satellite System

    Science.gov (United States)

    Engel, J. M.; Polling, D.; Ustamujic, F.; Yaldiz, R.; et al.

    2002-01-01

    (SPoTS) supplying other satellites with energy. SPoTS is due to be commercially viable and operative in 2020. of Technology designed the SPoTS during a full-time design period of six weeks as a third year final project. The team, organized according to the principles of systems engineering, first conducted a literature study on space wireless energy transfer to select the most suitable candidates for use on the SPoTS. After that, several different system concepts have been generated and evaluated, the most promising concept being worked out in greater detail. km altitude. Each SPoTS satellite has a 50m diameter inflatable solar collector that focuses all received sunlight. Then, the received sunlight is further redirected by means of four pointing mirrors toward four individual customer satellites. A market-analysis study showed, that providing power to geo-stationary communication satellites during their eclipse would be most beneficial. At arrival at geo-stationary orbit, the focused beam has expended to such an extent that its density equals one solar flux. This means that customer satellites can continue to use their regular solar arrays during their eclipse for power generation, resulting in a satellite battery mass reduction. the customer satellites in geo-stationary orbit, the transmitted energy beams needs to be pointed with very high accuracy. Computations showed that for this degree of accuracy, sensors are needed, which are not mainstream nowadays. Therefore further research must be conducted in this area in order to make these high-accuracy-pointing systems commercially attractive for use on the SPoTS satellites around 2020. Total 20-year system lifetime cost for 18 SPoT satellites are estimated at approximately USD 6 billion [FY2001]. In order to compete with traditional battery-based satellite power systems or possible ground based wireless power transfer systems the price per kWh for the customer must be significantly lower than the present one

  9. Verifying command sequences for satellite systems

    Science.gov (United States)

    Peters, James F., III; Ramanna, Sheela

    1992-10-01

    We present a formal basis for the design of a Checker used in validating safe schedules and in selecting error recovery schedules for satellite control systems. This design includes a high-level specification of Checker behavior and properties (called flight rules) of safe schedules. Specifications are written in Timed Linear Logic (TLL). Validation of schedules is performed in terms of real-time telemetry and deduction system proof rules. Telemetry (state information for satellite subsystems) serves as input to the Checker. Detection of violation of a flight rule by the Checker results in the selection of a contingency plan (error recovery schedule). The Checker is illustrated in terms of the TOPEX/Poseidon Oceanographic Satellite System.

  10. Results from a post-launch monitoring survey on consumer purchases of foods with added phytosterols in five European countries.

    Science.gov (United States)

    Willems, Julie I; Blommaert, Mireille A E; Trautwein, Elke A

    2013-12-01

    Phytosterols (plant sterols and stanols), in the form of phytosterol-esters, are used in food products as active ingredients to lower elevated blood low density lipoprotein-cholesterol concentrations. In Europe, plant sterol-esters gained Novel Foods authorisation in 2000. As a requirement of the authorisation, Unilever developed a post-launch monitoring program to monitor the use of products with added phytosterols. This paper reports findings from the 2011 post-launch monitoring survey on consumer purchase behaviour of foods with added phytosterols. 91,000 households in the Netherlands, Belgium, United Kingdom, France and Germany were included. 11,612 purchased foods with added phytosterols, including spreads, salad dressings, milk- and yoghurt-type products. The results show that 71-82% of households purchasing products with added phytosterols were 1-2 person households. These households were also purchasing the majority of the volume sold in each country (75-85%). The average phytosterol intakes per household were 0.35-0.86 g/day; well below the 1.5-3.0 g/day phytosterols needed to achieve a significant blood cholesterol lowering benefit. Post-launch monitoring is an accepted and useful tool to estimate the consumption behaviour amongst different consumer groups. Data show that average phytosterol intakes per household were well below 1g/day, suggesting that overconsumption is unlikely. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. A relativistic and autonomous navigation satellite system

    CERN Document Server

    Delva, Pacôme; Kostić, Uros; Carloni, Sante

    2011-01-01

    A relativistic positioning system has been proposed by Bartolom\\'e Coll in 2002. Since then, several group developed this topic with different approaches. I will present a work done in collaboration with Ljubljana University and the ESA Advanced Concepts Team. We developed a concept, Autonomous Basis of Coordinates, in order to take advantage of the full autonomy of a satellite constellation for navigation and positioning, by means of satellite inter-links. I will present the advantages of this new paradigm and a number of potential application for reference systems, geophysics and relativistic gravitation.

  12. Advantages of Hybrid Global Navigation Satellite Systems

    Directory of Open Access Journals (Sweden)

    Asim Bilajbegović

    2007-05-01

    Full Text Available In a decision-making situation, what kind of GPS equipment to purchase, one always has a dilemma, tobuy hybrid (GPS+GLONASS or only GPS receivers? In the case of completeness of the GLONASS satellite system, this dilemma probably would not have existed. The answer to this dilemma is given in the present paper, but for the constellation of the GLONASS satellites in summer 2006 (14 satellites operational. Due to the short operational period of these satellites (for example GLONASS-M, 5 years, and not launching new ones, at this moment (February 25, 2007, only 10 satellites are operational. For the sake of research and giving answers to these questions, about 252 RTK measurements have been done using (GPS and GNSS receivers, on points with different obstructions of horizon. Besides that, initialisation time has been investigated for both systems from about 480 measurements, using rover's antenna with metal cover, during a time interval of 0.5, 2 and 5 seconds. Moreover, accuracy, firmware declared accuracy and redundancy of GPS and GNSS RTK measurements have been investigating.  

  13. A native IP satellite communications system

    Science.gov (United States)

    Koudelka, O.; Schmidt, M.; Ebert, J.; Schlemmer, H.; Kastner-Puschl, S.; Riedler, W.

    2004-08-01

    ≪ In the framework of ESA's ARTES-5 program the Institute of Applied Systems Technology (Joanneum Research) in cooperation with the Department of Communications and Wave Propagation has developed a novel meshed satellite communications system which is optimised for Internet traffic and applications (L*IP—Local Network Interconnection via Satellite Systems Using the IP Protocol Suite). Both symmetrical and asymmetrical connections are supported. Bandwidth on demand and guaranteed quality of service are key features of the system. A novel multi-frequency TDMA access scheme utilises efficient methods of IP encapsulation. In contrast to other solutions it avoids legacy transport network techniques. While the DVB-RCS standard is based on ATM or MPEG transport cells, the solution of the L*IP system uses variable-length cells which reduces the overhead significantly. A flexible and programmable platform based on Linux machines was chosen to allow the easy implementation and adaptation to different standards. This offers the possibility to apply the system not only to satellite communications, but provides seamless integration with terrestrial fixed broadcast wireless access systems. The platform is also an ideal test-bed for a variety of interactive broadband communications systems. The paper describes the system architecture and the key features of the system.

  14. Neptunian Satellites observed with Keck AO system

    Science.gov (United States)

    Marchis, F.; Urata, R.; de Pater, I.; Gibbard, S.; Hammel, H. B.; Berthier, J.

    2004-05-01

    The Neptunian system was observed on 9 different nights between July 2002 and October 2003 with the 10-m Keck telescope on Mauna Kea, Hawaii, and its facility instrument NIRC2 coupled with the Adaptive Optics system. Data were recorded in J (1.2μ m), and H (2.2μ m) bands. The angular resolution achieved on a one-minute integration time image is 0.50 arcsec, corresponding to a spatial resolution of 1100 km. The images display small structures such as the rings (de Pater et al. 2004), clouds in the atmosphere (Gibbard et al. 2003), and inner satellites, mainly Proteus, Larissa, Galatea, Despina, and Thalassa. On the 40 images, the positions and intensities of the satellites detected were accurately measured fitting the signal with a gaussian profile. The center of Neptune was obtained by fitting the disk position with an ellipse. After correcting for the detector distortion, we compared the satellite positions with the predicted ones delivered by several ephemerides. We used the JPL (NEP016 + NEP022 + DE405) and two IMCCE ephemerides, an old version (VSOP87+Owen et al., 1991) and a more recent one (DE405+Le Guyader et al., 1993). All cases, we confirmed the presence of an apparent shift between the predicted and the observed positions. Table 1 (see http://astron.berkeley.edu/ fmarchis/Science/Neptune/Satellites/) summarizes the mean distance of the shift for satellites most frequently observed and the various ephemerides. In this presentation, we will report the positions of the satellites, and present their color and possible photometric variations derived from the observations. This work has been partially supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783.

  15. Networks for Autonomous Formation Flying Satellite Systems

    Science.gov (United States)

    Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

    2001-01-01

    The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  16. Communications satellite system for Africa

    Science.gov (United States)

    Kriegl, W.; Laufenberg, W.

    1980-09-01

    Earlier established requirement estimations were improved upon by contacting African administrations and organizations. An enormous demand is shown to exist for telephony and teletype services in rural areas. It is shown that educational television broadcasting should be realized in the current African transport and communications decade (1978-1987). Radio broadcasting is proposed in order to overcome illiteracy and to improve educational levels. The technical and commercial feasibility of the system is provided by computer simulations which demonstrate how the required objectives can be fulfilled in conjunction with ground networks.

  17. Technology for a quasi-GSO satellite communications system

    OpenAIRE

    Katagi, T.; Yonezawa, R.; Chiba, I.; Urasaki, S.

    1999-01-01

    In this paper, a satellite communications system using a Quasi Geostationary Satellite Orbit (Quasi-GSO) is proposed. A 24-hour period Quasi-GSO system could give high quality communication to high latitude regions with its satellites observed from earth stations having high elevation angles. In this paper, a system concept and a deployable flat antenna with light weight antenna elements are described proposing it to be a good candidate for mobile communications satellite use.

  18. The NOAA Satellite Observing System Architecture Study

    Science.gov (United States)

    Volz, Stephen; Maier, Mark; Di Pietro, David

    2016-01-01

    NOAA is beginning a study, the NOAA Satellite Observing System Architecture (NSOSA) study, to plan for the future operational environmental satellite system that will follow GOES and JPSS, beginning about 2030. This is an opportunity to design a modern architecture with no pre-conceived notions regarding instruments, platforms, orbits, etc. The NSOSA study will develop and evaluate architecture alternatives to include partner and commercial alternatives that are likely to become available. The objectives will include both functional needs and strategic characteristics (e.g., flexibility, responsiveness, sustainability). Part of this study is the Space Platform Requirements Working Group (SPRWG), which is being commissioned by NESDIS. The SPRWG is charged to assess new or existing user needs and to provide relative priorities for observational needs in the context of the future architecture. SPRWG results will serve as input to the process for new foundational (Level 0 and Level 1) requirements for the next generation of NOAA satellites that follow the GOES-R, JPSS, DSCOVR, Jason-3, and COSMIC-2 missions.

  19. Incoherent correlator system for satellite orientation control

    Science.gov (United States)

    Kouris, Aristodemos; Young, Rupert C. D.; Chatwin, Christopher R.; Birch, Philip M.

    2002-03-01

    An incoherent correlator configuration is proposed and experimentally demonstrated that is capable of recognizing star patterns. The device may thus be employed for the orientation and navigation of a satellite or spacecraft. The correlator employs starlight directly and requires no laser or input spatial light modulator for operation. The filter is constructed form an array of mirrors that may be individually appropriately tilted so as recognize a particular star arrangement. The only other components of the system are a converging lens and CCD array detector. The device is capable of determining the pointing direction and rotation of a satellite or space vehicle. Experimental results employing the mirror array device illuminated with a point source early to simulate starlight are presented.

  20. System implementation for Earth Radiation Budget Satellite System

    Science.gov (United States)

    Cooper, J. E.; Woerner, C. V.

    1978-01-01

    A description is presented of the instrument system which is needed for the Earth Radiation Budget Satellite System (ERBSS). The system is to be composed of instruments on two of NOAA's near-polar sun-synchronous Tiros-N/NOAA A through G series of operational satellites and on a NASA midinclination satellite of the Applications Explorer Mission (AEM) type referred to as ERBS-A/AEM. The Tiros-N/NOAA satellites will be in nominal 833 km altitude circular orbits with orbital inclinations of 98 deg. The AEM satellite will be in a circular orbit with an inclination of approximately 56 deg and a nominal altitude of 600 km. Each satellite will carry wide field-of-view (WFOV) and medium field-of-view (MFOV) sensors, a sensor for measuring the solar constant, and a narrow field-of-view (NFOV) cross-track scanner. The conceptual design of the W/MFOV instrument is discussed along with the conceptual design of the scanner.

  1. Technical comparison of several global mobile satellite communications systems

    Science.gov (United States)

    Comparetto, Gary M.

    The era of satellite-based mobile satellite communications (MSC) systems started with the first MARISAT satellite which was launched into a geostationary orbit over the Pacific Ocean in 1976 to provide communications between ships and shore stations. The combination of high cost and unacceptably large equipment has kept the space-based MSC systems from appealing to the wider market of personal mobile communications. The progress made over the last ten years, however, in digital voice processing, satellite technology, and component miniaturization has resulted in the viability of satellite-based mobile satellite communications systems to meet the growing market in personal mobile communications using handsets similar to those currently in use with land-based cellular systems. Three of the more mature LEO/MEO satellite systems are addressed in this paper including GLOBALSTAR, Iridium, and Odyssey. The system architectures of each system are presented along with a description of the satellite and user handset designs and the multiaccess techniques employed. It will be shown that, although a number of similarities exist among the system addressed, each system is unique in a variety of significant design areas. It is concluded that the technical feasibility of satellite-based mobile satellite communications systems seems to be secure. It will be challenging, however, for the vendors to actually develop and deploy these systems in a cost effective, timely, and reliable way that meets a continually evolving set of requirements based upon a rapidly changing technology base.

  2. Optimal Release Control of Companion Satellite System Using Electromagnetic Forces

    Institute of Scientific and Technical Information of China (English)

    Zengwen Xu,Peng Shi; Yushan Zhao∗

    2015-01-01

    Electromagnetic forces generated by the inter⁃action of component satellites can be used to release companion satellites. Optimal release trajectories for companion satellite system using inter⁃electromagnetic forces were investigated. Firstly, nonlinear relative motion dynamic equations of a two⁃craft electromagnetic companion satellite system were derived in spatial polar coordinates. Then principles of electromagnetic satellite formation flying were introduced. Secondly, the characteristics of the electromagnetic companion satellites release were analyzed and optimal release trajectories of companion satellites using electromagnetic forces were obtained using Gauss pseudospectral method. Three performance criteria were chosen as minimum time, minimum acceleration of the separation distance and minimum control acceleration. Finally, three release examples including expansion along separation distance, rotation in orbital plane and stable formation reconfiguration were given to demonstrate the feasibility of this method. Results indicated that the release trajectories can converge to optimal solutions effectively and the concept of release companion satellites using electromagnetic forces is practicable.

  3. National Satellite Forest Monitoring systems for REDD+

    Science.gov (United States)

    Jonckheere, I. G.

    2012-12-01

    Reducing Emissions from Deforestation and Forest Degradation (REDD) is an effort to create a financial value for the carbon stored in forests, offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. "REDD+" goes beyond deforestation and forest degradation, and includes the role of conservation, sustainable management of forests and enhancement of forest carbon stocks. In the framework of getting countries ready for REDD+, the UN-REDD Programme assists developing countries to prepare and implement national REDD+ strategies. For the monitoring, reporting and verification, FAO supports the countries to develop national satellite forest monitoring systems that allow for credible measurement, reporting and verification (MRV) of REDD+ activities. These are among the most critical elements for the successful implementation of any REDD+ mechanism. The UN-REDD Programme through a joint effort of FAO and Brazil's National Space Agency, INPE, is supporting countries to develop cost- effective, robust and compatible national monitoring and MRV systems, providing tools, methodologies, training and knowledge sharing that help countries to strengthen their technical and institutional capacity for effective MRV systems. To develop strong nationally-owned forest monitoring systems, technical and institutional capacity building is key. The UN-REDD Programme, through FAO, has taken on intensive training together with INPE, and has provided technical help and assistance for in-country training and implementation for national satellite forest monitoring. The goal of the support to UN-REDD pilot countries in this capacity building effort is the training of technical forest people and IT persons from interested REDD+ countries, and to set- up the national satellite forest monitoring systems. The Brazilian forest monitoring system, TerraAmazon, which is used as a basis for this initiative, allows

  4. Joint Polar Satellite System Common Ground System Overview

    Science.gov (United States)

    Jamilkowski, M. L.; Miller, S. W.; Grant, K. D.

    2012-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, JPSS replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The JPSS CGS currently provides data processing for Suomi NPP, generating multiple terabytes per day across over two dozen environmental data products; that workload will be multiplied by two when the JPSS-1 satellite is

  5. System architecture for the Canadian interim mobile satellite system

    Science.gov (United States)

    Shariatmadar, M.; Gordon, K.; Skerry, B.; Eldamhougy, H.; Bossler, D.

    1988-05-01

    The system architecture for the Canadian Interim Mobile Satellite Service (IMSS) which is planned for commencement of commercial service in late 1989 is reviewed. The results of an associated field trial program which was carried out to determine the limits of coverage and the preliminary performance characteristics of the system are discussed.

  6. Satellite power system (SPS) public outreach experiment

    Energy Technology Data Exchange (ETDEWEB)

    McNeal, S.R.

    1980-12-01

    To improve the results of the Satellite Power System (SPS) Concept Development and Evaluation Program, an outreach experiment was conducted. Three public interest groups participated: the L-5 Society (L-5), Citizen's Energy Project (CEP), and the Forum for the Advancement of Students in Science and Technology (FASST). Each group disseminated summary information about SPS to approximately 3000 constituents with a request for feedback on the SPS concept. The objectives of the outreach were to (1) determine the areas of major concern relative to the SPS concept, and (2) gain experience with an outreach process for use in future public involvement. Due to the combined efforts of all three groups, 9200 individuals/organizations received information about the SPS concept. Over 1500 receipients of this information provided feedback. The response to the outreach effort was positive for all three groups, suggesting that the effort extended by the SPS Project Division to encourage an information exchange with the public was well received. The general response to the SPS differed with each group. The L-5 position is very much in favor of SPS; CEP is very much opposed and FASST is relatively neutral. The responses are analyzed, and from the responses some questions and answers about the satellite power system are presented in the appendix. (WHK)

  7. SAW based systems for mobile communications satellites

    Science.gov (United States)

    Peach, R. C.; Miller, N.; Lee, M.

    1993-01-01

    Modern mobile communications satellites, such as INMARSAT 3, EMS, and ARTEMIS, use advanced onboard processing to make efficient use of the available L-band spectrum. In all of these cases, high performance surface acoustic wave (SAW) devices are used. SAW filters can provide high selectivity (100-200 kHz transition widths), combined with flat amplitude and linear phase characteristics; their simple construction and radiation hardness also makes them especially suitable for space applications. An overview of the architectures used in the above systems, describing the technologies employed, and the use of bandwidth switchable SAW filtering (BSSF) is given. The tradeoffs to be considered when specifying a SAW based system are analyzed, using both theoretical and experimental data. Empirical rules for estimating SAW filter performance are given. Achievable performance is illustrated using data from the INMARSAT 3 engineering model (EM) processors.

  8. Global Ocean Surveillance With Electronic Intelligence Based Satellite System

    Science.gov (United States)

    Venkatramanan, Haritha

    2016-07-01

    The objective of this proposal is to design our own ELINT based satellite system to detect and locate the target by using satellite Trilateration Principle. The target position can be found by measuring the radio signals arrived at three satellites using Time Difference of Arrival(TDOA) technique. To locate a target it is necessary to determine the satellite position. The satellite motion and its position is obtained by using Simplified General Perturbation Model(SGP4) in MATLAB. This SGP4 accepts satellite Two Line Element(TLE) data and returns the position in the form of state vectors. These state vectors are then converted into observable parameters and then propagated in space. This calculations can be done for satellite constellation and non - visibility periods can be calculated. Satellite Trilateration consists of three satellites flying in formation with each other. The satellite constellation design consists of three satellites with an inclination of 61.3° maintained at equal distances between each other. The design is performed using MATLAB and simulated to obtain the necessary results. The target's position can be obtained using the three satellites ECEF Coordinate system and its position and velocity can be calculated in terms of Latitude and Longitude. The target's motion is simulated to obtain the Speed and Direction of Travel.

  9. Communication satellite system beyond the year 2000

    Science.gov (United States)

    Robertson, G. J.; Fourquet, J. M.

    1991-10-01

    The primary evolutionary factors of satellite communications technologies are reviewed based on the results of a study of novel satellite developments. A critical evaluation of the viability and availability of the technologies is utilized in conjunction with market forecasts to determine promising commercial strategies. Modern technologies are almost prepared for the development of a class of communications satellites and include bandwidth utilization, spacecraft bus modularity, and functional integration.

  10. Simultaneous single epoch satellite clock modelling in Global Navigation Satellite Systems

    Science.gov (United States)

    Thongtan, Thayathip

    In order to obtain high quality positions from navigation satellites, range errors have to be identified and either modelled or estimated. This thesis focuses on satellite clock errors, which are needed to be known because satellite clocks are not perfectly synchronised with navigation system time. A new approach, invented at UCL, for the simultaneous estimation, in a single epoch, of all satellite clock offsets within a Global Navigation Satellite System (GNSS) from range data collected at a large number of globally distributed ground stations is presented. The method was originally tested using only data from a limited number of GPS satellites and ground stations. In this work a total of 50 globally distributed stations and the whole GPS constellation are used in order to investigate more fully the capabilities of the method, in terms of both accuracy and reliability. A number of different estimation models have been tested. These include those with different weighting schemes, those with and without tropospheric bias parameters and those that include assumptions regarding prior knowledge of satellite orbits. In all cases conclusions have been drawn based on formal error propagation theory. Accuracy has been assessed largely through the sizes of the predicted satellite clock standard deviations and, in the case of simultaneously estimating satellite positions, their error ellipsoids. Both internal and external reliability have been assessed as these are important contributors to integrity, something that is essential for many practical applications. It has been found that the accuracy and reliability of satellite clock offsets are functions of the number of known ground station clocks and distance from them, quality of orbits and quality of range measurement. Also the introduction of tropospheric zenith delay parameters into the model reduces both accuracy and reliability by amounts depending on satellite elevation angles. (Abstract shortened by UMI.)

  11. Global navigation satellite system; Jisedai kokoho senjo system

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, S.; Suga, S. [Toshiba Corp., Tokyo (Japan)

    2000-05-01

    The safety of civil aviation relies on ground navigation aids. In areas where there are no ground aids and on oceanic air routes, aircraft must depend on their own navigation system. The predicted increase in civil aviation traffic in the near future will make it difficult for current navigation aids to support navigation in all phases of flights. To avoid this problem, the International Civil Aviation Organization (ICAO) is directing the establishment of standards for the global navigation satellite system (GNSS). GNSS employs navigation satellites, such as those of the global positioning system (GPS), to provide navigation capability throughout the world. In Japan, the Electronic Navigation Research Institute, the Ministry of Transport, and the Japan civil Aviation Promotion Foundation are carrying out research on this navigation system. Toshiba has been providing experimental equipment for this research. (author)

  12. Satellite data assimilation in global forecast system in India

    Science.gov (United States)

    Basu, Swati

    2014-11-01

    Satellite data is very important for model initialization and verification. A large number of satellite observations are currently assimilated into the Numerical Weather Prediction (NWP) systems at the National Centre for Medium Range Weather Forecasting (NCMRWF). Apart from Global meteorological observations from GTS, near-real time satellite observations are received at NCMRWF from other operational centres like ISRO, NOAA/NESDIS, EUMETCAST, etc. Recently India has become member of Asia-Pacific Regional ATOVS Retransmission Service (APRARS) for faster access to high resolution global satellite data useful for high resolution regional models. Indian HRPT at Chennai covers the APRARS data gap region over South East Asia. A robust data monitoring system has been implemented at NCMRWF to assess the quantity and quality of the data as well as the satellite sensor strength, before getting assimilated in the models. Validation of new satellite observations, especially from Indian satellites are being carried out against insitu observations and similar space borne platforms. After establishing the quality of the data, Observation System Experiments (OSEs) are being conducted to study their impact in the assimilation and forecast systems. OSEs have been carried out with the Oceansat-2 scatterometer winds and radiance data from Megha-Tropiques SAPHIR sensor. Daily rainfall analysis dataset is being generated by merging satellite estimates and in-situ observations. ASCAT soil wetness measurements from METOP satellite is being assimilated into the global model. Land surface parameters (LuLc and albedo) retrieved from Indian satellites are being explored for its possible usage in the global and regional models. OLR from Indian satellites are used for validating model outputs. This paper reviews the efforts made at NCMRWF in (i) assimilating the data from Indian/International satellites and (ii) generating useful products from the satellite data.

  13. GNSS global navigation satellite systems : GPS, GLONASS, Galileo, and more

    CERN Document Server

    Hofmann-Wellenhof, Bernhard; Wasle, Elmar

    2008-01-01

    This book is an extension to the acclaimed scientific bestseller "GPS - Theory and Practice". It covers Global Navigation Satellite Systems (GNSS) and includes the Russian GLONASS, the European system Galileo, and additional systems.

  14. Computer-Aided Communication Satellite System Analysis and Optimization.

    Science.gov (United States)

    Stagl, Thomas W.; And Others

    Various published computer programs for fixed/broadcast communication satellite system synthesis and optimization are discussed. The rationale for selecting General Dynamics/Convair's Satellite Telecommunication Analysis and Modeling Program (STAMP) in modified form to aid in the system costing and sensitivity analysis work in the Program on…

  15. An Instructional Satellite System for the United States: Preliminary Considerations.

    Science.gov (United States)

    DuMolin, James R.; Morgan, Robert P.

    Based on educational, social, political, and other considerations, an instructional satellite system, AVSIN (Ausio-Visual Satellite Instruction), is hypothesized which represents one possible organizational and administrative arrangement for delivering large amounts of quality software to schools and learning centers. The AVSIN system is conceived…

  16. Power Processing Unit For Micro Satellite Electric Propulsion System

    Directory of Open Access Journals (Sweden)

    Savvas Spiridon

    2017-01-01

    Full Text Available The Micro Satellite Electric Propulsion System (MEPS program has been originated by the increasing need to provide a low-cost and low-power Electric Propulsion System (EPS for small satellites ( 92%, small size and weight and high reliability. Its functional modules and preliminary results obtained at breadboard level are also presented.

  17. Evaluation of CDMA system capacity for mobile satellite system applications

    Science.gov (United States)

    Smith, Partrick O.; Geraniotis, Evaggelos A.

    1988-01-01

    A specific Direct-Sequence/Pseudo-Noise (DS/PN) Code-Division Multiple-Access (CDMA) mobile satellite system (MSAT) architecture is discussed. The performance of this system is evaluated in terms of the maximum number of active MSAT subscribers that can be supported at a given uncoded bit-error probability. The evaluation decouples the analysis of the multiple-access capability (i.e., the number of instantaneous user signals) from the analysis of the multiple-access mutliplier effect allowed by the use of CDMA with burst-modem operation. We combine the results of these two analyses and present numerical results for scenarios of interest to the mobile satellite system community.

  18. System refinement for content based satellite image retrieval

    Directory of Open Access Journals (Sweden)

    NourElDin Laban

    2012-06-01

    Full Text Available We are witnessing a large increase in satellite generated data especially in the form of images. Hence intelligent processing of the huge amount of data received by dozens of earth observing satellites, with specific satellite image oriented approaches, presents itself as a pressing need. Content based satellite image retrieval (CBSIR approaches have mainly been driven so far by approaches dealing with traditional images. In this paper we introduce a novel approach that refines image retrieval process using the unique properties to satellite images. Our approach uses a Query by polygon (QBP paradigm for the content of interest instead of using the more conventional rectangular query by image approach. First, we extract features from the satellite images using multiple tiling sizes. Accordingly the system uses these multilevel features within a multilevel retrieval system that refines the retrieval process. Our multilevel refinement approach has been experimentally validated against the conventional one yielding enhanced precision and recall rates.

  19. Development of environmental monitoring satellite systems in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With the increase in global environmental problems,the necessity and urgency of remote sensing technology being applied to environmental monitoring has been widely recognized around the world.China has launched the environment and disaster monitoring and forecasting small satellite constellation HJ-1A/B and the FY3 atmosphere and environmental satellite,but they still cannot fully satisfy requirements for environmental monitoring.This paper summarizes the current status of satellite environmental monitoring in China and the existing problems of inadequate load design and low data utilization efficiency,and discusses the demand for environmental monitoring satellites.Based on the development of foreign satellite systems for environmental monitoring,the future development and key tasks of the environmental monitoring satellite system in China is discussed,as are some related initiatives.

  20. Network coding and its applications to satellite systems

    DEFF Research Database (Denmark)

    Vieira, Fausto; Roetter, Daniel Enrique Lucani

    2015-01-01

    Network coding has its roots in information theory where it was initially proposed as a way to improve a two-node communication using a (broadcasting) relay. For this theoretical construct, a satellite communications system was proposed as an illustrative example, where the relay node would...... be a satellite covering the two nodes. The benefits in terms of throughput, resilience, and flexibility of network coding are quite relevant for wireless networks in general, and for satellite systems in particular. This chapter presents some of the basics in network coding, as well as an overview of specific...... scenarios where network coding provides a significant improvement compared to existing solutions, for example, in broadcast and multicast satellite networks, hybrid satellite-terrestrial networks, and broadband multibeam satellites. The chapter also compares coding perspectives and revisits the layered...

  1. Network coding and its applications to satellite systems

    DEFF Research Database (Denmark)

    Vieira, Fausto; Roetter, Daniel Enrique Lucani

    2015-01-01

    Network coding has its roots in information theory where it was initially proposed as a way to improve a two-node communication using a (broadcasting) relay. For this theoretical construct, a satellite communications system was proposed as an illustrative example, where the relay node would...... be a satellite covering the two nodes. The benefits in terms of throughput, resilience, and flexibility of network coding are quite relevant for wireless networks in general, and for satellite systems in particular. This chapter presents some of the basics in network coding, as well as an overview of specific...... scenarios where network coding provides a significant improvement compared to existing solutions, for example, in broadcast and multicast satellite networks, hybrid satellite-terrestrial networks, and broadband multibeam satellites. The chapter also compares coding perspectives and revisits the layered...

  2. Reusable Reentry Satellite (RRS) system design study

    Science.gov (United States)

    1991-01-01

    The Reusable Reentry Satellite (RRS) is intended to provide investigators in several biological disciplines with a relatively inexpensive method to access space for up to 60 days with eventual recovery on Earth. The RRS will permit totally intact, relatively soft, recovery of the vehicle, system refurbishment, and reflight with new and varied payloads. The RRS is to be capable of three reflights per year over a 10-year program lifetime. The RRS vehicle will have a large and readily accessible volume near the vehicle center of gravity for the Payload Module (PM) containing the experiment hardware. The vehicle is configured to permit the experimenter late access to the PM prior to launch and rapid access following recovery. The RRS will operate in one of two modes: (1) as a free-flying spacecraft in orbit, and will be allowed to drift in attitude to provide an acceleration environment of less than 10(exp -5) g. the acceleration environment during orbital trim maneuvers will be less than 10(exp -3) g; and (2) as an artificial gravity system which spins at controlled rates to provide an artificial gravity of up to 1.5 Earth g. The RRS system will be designed to be rugged, easily maintained, and economically refurbishable for the next flight. Some systems may be designed to be replaced rather than refurbished, if cost effective and capable of meeting the specified turnaround time. The minimum time between recovery and reflight will be approximately 60 days. The PMs will be designed to be relatively autonomous, with experiments that require few commands and limited telemetry. Mass data storage will be accommodated in the PM. The hardware development and implementation phase is currently expected to start in 1991 with a first launch in late 1993.

  3. Space Solar Power Satellite Systems, Modern Small Satellites, and Space Rectenna

    Science.gov (United States)

    Bergsrud, Corey Alexis Marvin

    Space solar power satellite (SSPS) systems is the concept of placing large satellite into geostationary Earth orbit (GEO) to harvest and convert massive amounts of solar energy into microwave energy, and to transmit the microwaves to a rectifying antenna (rectenna) array on Earth. The rectenna array captures and converts the microwave power into usable power that is injected into the terrestrial electric grid for use. This work approached the microwave power beam as an additional source of power (with solar) for lower orbiting satellites. Assuming the concept of retrodirectivity, a GEO-SSPS antenna array system tracks and delivers microwave power to lower orbiting satellites. The lower orbiting satellites are equipped with a stacked photovoltaic (PV)/rectenna array hybrid power generation unit (HPGU) in order to harvest solar and/or microwave energy for on-board use during orbit. The area, and mass of the PV array part of the HPGU was reduced at about 32% beginning-of-life power in order to achieve the spacecraft power requirements. The HPGU proved to offer a mass decrease in the PGU, and an increase in mission life due to longer living component life of the rectenna array. Moreover, greater mission flexibility is achieved through a track and power delivery concept. To validate the potential advantages offered by a HPGU, a mission concept was presented that utilizes modern small satellites as technology demonstrators. During launch, a smaller power receiving "daughter" satellite sits inside a larger power transmitting "mother" satellite. Once separated from the launch vehicle the daughter satellite is ejected away from the mother satellite, and each satellite deploys its respective power transmitting or power receiving hardware's for experimentation. The concept of close proximity mission operations between the satellites is considered. To validate the technology of the space rectenna array part of the HPGU, six milestones were completed in the design. The first

  4. Study on fault locating technology for satellite power system

    Institute of Scientific and Technical Information of China (English)

    LONG Bing; JIANG Xing-wei; SONG Zheng-ji

    2005-01-01

    It is currently prevalent to locate faults for a satellite power system based on an expert system, not utilizing all the available information provided by tests. The casual network model for a satellite power system is presented. Considerations for failure probability of each component of the power system, the cost of applying each test, the influence of a precedent test result on the next test selection, and an optimal sequential testing algorithm for fault location is presented. This program is applied to locate the failure component of the power system of a satellite. The results show this program is very effective and it is very fast to generate an optimal diagnosis tree.

  5. The satellite based augmentation system – EGNOS for non-precision approach global navigation satellite system

    Directory of Open Access Journals (Sweden)

    Andrzej FELLNER

    2012-01-01

    Full Text Available First in the Poland tests of the EGNOS SIS (Signal in Space were conducted on 5th October 2007 on the flight inspection with SPAN (The Synchronized Position Attitude Navigation technology at the Mielec airfield. This was an introduction to a test campaign of the EGNOS-based satellite navigation system for air traffic. The advanced studies will be performed within the framework of the EGNOS-APV project in 2011. The implementation of the EGNOS system to APV-I precision approach operations, is conducted according to ICAO requirements in Annex 10. Definition of usefulness and certification of EGNOS as SBAS (Satellite Based Augmentation System in aviation requires thorough analyses of accuracy, integrity, continuity and availability of SIS. Also, the project will try to exploit the excellent accuracy performance of EGNOS to analyze the implementation of GLS (GNSS Landing System approaches (Cat I-like approached using SBAS, with a decision height of 200 ft. Location of the EGNOS monitoring station Rzeszów, located near Polish-Ukrainian border, being also at the east border of planned EGNOS coverage for ECAC states is very useful for SIS tests in this area. According to current EGNOS programmed schedule, the project activities will be carried out with EGNOS system v2.2, which is the version released for civil aviation certification. Therefore, the project will allow demonstrating the feasibility of the EGNOS certifiable version for civil applications.

  6. Integration Of GPS And GLONASS Systems In Geodetic Satellite Measurements

    Science.gov (United States)

    Maciuk, Kamil

    2015-12-01

    The article shows the results of satellites measurements elaborations using GPS & GLONASS signals. The aim of this article is to define the influence of adding GLONASS signals on position determination accuracy. It especially concerns areas with big horizon coverages. Object of the study were analysis of DOP coefficients, code and RTK solutions, and usage of satellite techniques in levelling. The performed studies and analysis show that integrated GPS-GLONASS satellite measurements provide possibility to achieve better results than measurements using single navigation satellite system (GPS).

  7. Morphology of Dwarf Galaxies in Isolated Satellite Systems

    Science.gov (United States)

    Ann, Hong Bae

    2017-08-01

    The environmental dependence of the morphology of dwarf galaxies in isolated satellite systems is analyzed to understand the origin of the dwarf galaxy morphology using the visually classified morphological types of 5836 local galaxies with z ≲ 0.01. We consider six sub-types of dwarf galaxies, dS0, dE, dE_{bc}, dSph, dE_{blue}, and dI, of which the first four sub-types are considered as early-type and the last two as late-type. The environmental parameters we consider are the projected distance from the host galaxy (r_{p}), local and global background densities, and the host morphology. The spatial distributions of dwarf satellites of early-type galaxies are much different from those of dwarf satellites of late-type galaxies, suggesting the host morphology combined with r_{p} plays a decisive role on the morphology of the dwarf satellite galaxies. The local and global background densities play no significant role on the morphology of dwarfs in the satellite systems hosted by early-type galaxies. However, in the satellite system hosted by late-type galaxies, the global background densities of dE and dSph satellites are significantly different from those of dE_{bc}, dE_{blue}, and dI satellites. The blue-cored dwarf satellites (dE_{bc}) of early-type galaxies are likely to be located at r_{p} > 0.3 Mpc to keep their cold gas from the ram pressure stripping by the hot corona of early-type galaxies. The spatial distribution of dE_{bc} satellites of early-type galaxies and their global background densities suggest that their cold gas is intergalactic material accreted before they fall into the satellite systems.

  8. Stability of Satellites in Closely Packed Planetary Systems

    CERN Document Server

    Payne, Matthew J; Holman, Matthew J; Perets, Hagai B

    2013-01-01

    We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary Systems with Tightly-packed Inner Planets (STIPs). We find that the majority of closely-spaced stable two-planet systems can stably support satellites across a range of parameter-space which is only slightly decreased compared to that seen for the single-planet case. In particular, circular prograde satellites remain stable out to $\\sim 0.4 R_H$ (where $R_H$ is the Hill Radius) as opposed to $\\sim 0.5 R_H$ in the single-planet case. A similarly small restriction in the stable parameter-space for retrograde satellites is observed, where planetary close approaches in the range 2.5 to 4.5 mutual Hill radii destabilize most satellites orbits only if $a\\sim 0.65 R_H$. In very close planetary pairs (e.g. the 12:11 resonance) the addition of a satellite frequently destabilizes the entire system, causing extreme close-approaches and the loss of satellites over a range of cir...

  9. Joint Polar Satellite System Common Ground System Overview

    Science.gov (United States)

    Jamilkowski, M. L.; Smith, D. C.

    2011-12-01

    Jointly acquired by NOAA & NASA, the next-generation civilian environmental satellite system, Joint Polar Satellite System (JPSS), will supply the afternoon orbit & ground system of the restructured NPOESS program. JPSS will replace NOAA's current POES satellites and the ground processing part of both POES & DoD's Defense Weather Satellite System (DWSS)(DMSP replacement). JPSS sensors will collect meteorological, oceanographic, climatological and solar-geophysical data. The ground system, or JPSS Common Ground System (CGS), has 6 integrated product teams/segments: Command, Control & Communications (C3S); Interface Data Processing (IDPS); Field Terminal (FTS); Systems Engineering, Integration & Test (SEIT); Operations & Support (O&S); and Sustainment developed by Raytheon Intelligence & Information Systems. The IDPS will process JPSS data to provide Environmental Data Records (EDRs) to NOAA & DoD processing centers beginning with the NPOESS Preparatory Project (NPP) and through JPSS & DWSS eras. C3S will: manage overall JPSS & DWSS missions from control/status of space/ground assets to ensure timely delivery of high-quality data to IDPS; provide globally-distributed ground assets to collect/transport mission, telemetry and command data between satellites & processing locations; provide all commanding & state-of-health monitoring functions of NPP, JPSS and DWSS satellites, and delivery of mission data to each Central IDP and monitor/report system-wide health/status and data communications with external systems and between CGS segments. SEIT leads the overall effort, including: manage/coordinate/execute JPSS CGS activities with NASA participation/oversight; plan/conduct all activities related to systems engineering, develop & ensure completeness of JPSS CGS functional & technical baselines and perform integration, deployment, testing and verification; sponsor/support modeling & simulation, performance analysis and trade studies; provide engineering for the product

  10. Analysis of Maritime Mobile Satellite Communication Systems

    Science.gov (United States)

    1988-12-01

    Communications and Surveil- lance, IEE, Conference publication n.95, 13-15 Mar. 1973. 2. Y. Karasawa and T. Shiokawa , Characteristics of L-Band Multipath Fading... Shiokawa . Analysis of M-ultipath Fading due to Sea Suface Scattering in Maritime Satellite Communication, Technical Group on Antennas and Propagation. IECE

  11. Isolated Galaxies and Isolated Satellite Systems

    CERN Document Server

    Ann, H B; Choi, Yun-Young

    2009-01-01

    We search for isolated galaxies using a volume-limited sample of galaxies with 0.02r_{vir,nei} and \\rho <\\bar{\\rho} well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests importance of hydrodynamic interaction among galaxies within their virial radii in galaxy evolution.

  12. Architecture analysis of the simplified libration point satellite navigation system

    Science.gov (United States)

    Zhang, Lei; Xu, Bo

    2016-10-01

    The libration point satellite navigation system is a novel navigation architecture that consists of satellites located in periodic orbits around the Earth-Moon libration points. Superiorities of the proposed system lie in its autonomy and extended navigation capability, which have been proved in our previous works. Based on the candidate architectures obtained before, a detailed analysis of the simplified libration point satellite navigation system, i.e. the Earth-Moon L1,2 two-satellite constellation, is conducted in this work. Firstly, relation between orbits amplitude is derived for the candidate two-satellite constellations to ensure continuous crosslink measurements between libration point satellites. Then, with the use of a reference lunar exploration mission scenario, navigation performances of different constellation configurations are evaluated by Monte-Carlo simulations. The simulation results indicate that the amplitude and initial phase combinations of libration point orbits have direct effect on the performance of the two-satellite constellations. By using a cooperative evolutionary algorithm for configuration parameter optimization, some optimal constellations are finally obtained for the simplified navigation architecture. The results obtained in this paper may be a reference for future system design.

  13. Use of CDMA access technology in mobile satellite systems

    Science.gov (United States)

    Ramasastry, Jay; Wiedeman, Bob

    1995-01-01

    Use of Code Division Multiple Access (CDMA) technology in terrestrial wireless systems is fairly well understood. Similarly, design and operation of Power Control in a CDMA-based system in a terrestrial environment is also well established. Terrestrial multipath characteristics, and optimum design of the CDMA receiver to deal with multipath and fading conditions are reliably established. But the satellite environment is different. When the CDMA technology is adopted to the satellite environment, other design features need to be incorporated (for example; interleaving, open-loop and closed-loop power control design, diversity characteristics) to achieve comparable level of system performance. In fact, the GLOBALSTAR LEO/MSS system has incorporated all these features. Contrary to some published reports, CDMA retains the advantages in the satellite environment that are similar to those achieved in the terrestrial environment. This document gives a description of the CDMA waveform and other design features adopted for mobile satellite applications.

  14. Intelligent fault isolation and diagnosis for communication satellite systems

    Science.gov (United States)

    Tallo, Donald P.; Durkin, John; Petrik, Edward J.

    1992-01-01

    Discussed here is a prototype diagnosis expert system to provide the Advanced Communication Technology Satellite (ACTS) System with autonomous diagnosis capability. The system, the Fault Isolation and Diagnosis EXpert (FIDEX) system, is a frame-based system that uses hierarchical structures to represent such items as the satellite's subsystems, components, sensors, and fault states. This overall frame architecture integrates the hierarchical structures into a lattice that provides a flexible representation scheme and facilitates system maintenance. FIDEX uses an inexact reasoning technique based on the incrementally acquired evidence approach developed by Shortliffe. The system is designed with a primitive learning ability through which it maintains a record of past diagnosis studies.

  15. Propagation considerations in the American Mobile Satellite system design

    Science.gov (United States)

    Kittiver, Charles; Sigler, Charles E., Jr.

    1993-01-01

    An overview of the American Mobile Satellite Corporation (AMSC) mobile satellite services (MSS) system with special emphasis given to the propagation issues that were considered in the design is presented. The aspects of the voice codec design that effect system performance in a shadowed environment are discussed. The strategies for overcoming Ku-Band rain fades in the uplink and downlink paths of the gateway station are presented. A land mobile propagation study that has both measurement and simulation activities is described.

  16. Design of House Keeping System for a Certain Micro Satellite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents the design of hardware and software of the house keeping system for a certain microsatellite. The system uses microelectronic technique, large scale integrated circuits, processors and computers which has the advantages of strong function, high flexibility and reliability, It satisfies the requirements for efficient performance,light weight, small volume,and low consumption of power for microsatellite.

  17. Satellite Attitude Control System Design considering the Fuel Slosh Dynamics

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Gadelha de Souza

    2014-01-01

    Full Text Available The design of the satellite attitude control system (ACS becomes more complex when the satellite structure has different type of components like, flexible solar panels, antennas, mechanical manipulators, and tanks with fuel. A crucial interaction can occur between the fuel slosh motion and the satellite rigid motion during translational and/or rotational manoeuvre since these interactions can change the satellite centre of mass position damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. As a result, the design of the satellite controller needs to explore the limits between the conflicting requirements of performance and robustness. This paper investigates the effects of the interaction between the liquid motion (slosh and the satellite dynamics in order to predict what the damage to the controller performance and robustness is. The fuel slosh dynamics is modelled by a pendulum which parameters are identified using the Kalman filter technique. This information is used to design the satellite controller by the linear quadratic regulator (LQR and linear quadratic Gaussian (LQG methods to perform a planar manoeuvre assuming thrusters are actuators.

  18. 622 Mbps High-speed satellite communication system for WINDS

    Science.gov (United States)

    Ogawa, Yasuo; Hashimoto, Yukio; Yoshimura, Naoko; Suzuki, Ryutaro; Gedney, Richard T.; Dollard, Mike

    2006-07-01

    WINDS is the experimental communications satellite currently under joint development by Japanese Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). The high-speed satellite communication system is very effective for quick deployment of high-speed networks economically. The WINDS will realize ultra high-speed networking and demonstrate operability of satellite communication systems in high-speed internet. NICT is now developing high-speed satellite communication system for WINDS. High-speed TDMA burst modem with high performance TPC error correction is underdevelopment. Up to the DAC on the transmitter and from the ADC on the receiver, all modem functions are performed in the digital processing technology. Burst modem has been designed for a user data rate up to 1244 Mbps. NICT is developing the digital terminal as a user interface and a network controller for this earth station. High compatibility with the Internet will be provided.

  19. Engineering satellite-based navigation and timing global navigation satellite systems, signals, and receivers

    CERN Document Server

    Betz, J

    2016-01-01

    This book describes the design and performance analysis of satnav systems, signals, and receivers. It also provides succinct descriptions and comparisons of all the world’s satnav systems. Its comprehensive and logical structure addresses all satnav signals and systems in operation and being developed. Engineering Satellite-Based Navigation and Timing: Global Navigation Satellite Systems, Signals, and Receivers provides the technical foundation for designing and analyzing satnav signals, systems, and receivers. Its contents and structure address all satnav systems and signals: legacy, modernized, and new. It combines qualitative information with detailed techniques and analyses, providing a comprehensive set of insights and engineering tools for this complex multidisciplinary field. Part I describes system and signal engineering including orbital mechanics and constellation design, signal design principles and underlying considerations, link budgets, qua tifying receiver performance in interference, and e...

  20. IMPGSS - International Medical Program Global Satellite System

    Science.gov (United States)

    2004-02-01

    additional comments regarding the significance of working with Tachyon and NASK under this Contract). 5.2.5 Requirements - Country/Region Assessments...services on a tentative exploratory basis by Tachyon ]. 5.2.7 Program Development Deliverable A 007 This is currently summarized in the Program Content...based satellite transmissions and transmission pricing based on segmented, limited use data volumes via Tachyon . " A more involved use of evaluation

  1. A Survey of Satellite Communications System Vulnerabilities

    Science.gov (United States)

    2008-06-01

    Myers, Raymond M. Nuber, Jaime L. Prieto , Jr., and Eric R. Wiswell, “Fast Packet Vs. Circuit Switch and Bent Pipe Satellite Network Architectures...2008. 81. Howell, Alan , “INMARSAT HORIZONS PROGRAM,” Institution of Electrical Engineers, Savoy Place, London, 1998. 82. http://www.infosec.gov.hk...ntia-rpt/02- 393/02-393.pdf, NTIA Report 02-393, pages 1-20, May 2002. 134. Sardella, Alan , “Securing Provider Backbone Networks: Packet Filters

  2. An operational satellite remote sensing system for ocean fishery

    Institute of Scientific and Technical Information of China (English)

    MAOZhihua; ZHUQiankun; PANDelu

    2004-01-01

    Ocean environmental information is very important to supporting the fishermen in fishing and satellite remote sensing technology can provide it in large scale and in near real-time. Ocean fishery locations are always far away beyond the coverage of the satellite data received by a land-based satellite receiving station. A nice idea is to install the satellite ground station on a fishing boat. When the boat moves to a fishery location, the station can receive the satellite data to cover the fishery areas. One satellite remote sensing system was once installed in a fishing boat and served fishing in the North Pacific fishery areas when the boat stayed there. The system can provide some oceanic environmental charts such as sea surface temperature (SST) and relevant derived products which are in most popular use in fishery industry. The accuracy of SST is the most important and affects the performance of the operational system, which is found to be dissatisfactory. Many factors affect the accuracy of SST and it is difficult to increase the accuracy by SST retrieval algorithms and clouds detection technology. A new technology of temperature error control is developed to detect the abnormity of satellite-measured SST. The performance of the technology is evaluated to change the temperature bias from-3.04 to 0.05 ℃ and the root mean square (RMS) from 5.71 to 1.75 ℃. It is suitable for employing in an operational satellite-measured SST system and improves the performance of the system in fishery applications. The system has been running for 3 a and proved to be very useful in fishing. It can help to locate the candidates of the fishery areas and monitor the typhoon which is very dangerous to the safety of fishing boats.

  3. Tsinghua-1 Micro-Satellite Power System Architecture and Design

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Tsinghua-1 Micro-satellite, the first satellite made by Tsinghua University, was launched in 2000. The power system of the Tsinghua-1 Micro-satellite is one of the most important subsystems. It provides all the power for the satellite platform and the payloads. The power system design includes the regulation,protection and distribution of a 4 × 35 W solar array and 7 Ah NiCd batteries. This subsystem essentially offerstwo buses: an unregulated 14 V bus and a regulated 5 V bus. All distributed power lines to the users areprotected by current tripping switches. In addition, some essential loads, such as the tele-command system,are supplied through fuses. The Tsinghua-1 Micro-satellite power system provides an efficient, flexible,reliable, and cost-effective solution for small satellites in low earth orbit. A better maximum power pointtracking method has been used to increase reliability margins and to increase the efficiency of the powersystem. The power system reliability was evaluated using several different tests, such as the power boardtest, the assembly integrate test (AIT), the electromagnetic compatibility (EMC) test and the thermal vacuumtest (TVT).``

  4. The Submillimeter Wave Astronomy Satellite (SWAS) solar array system

    Science.gov (United States)

    Sneiderman, Gary

    1993-01-01

    The SWAS (Submillimeter Wave Astronomy Satellite) solar array system is described. It is an innovative approach to meet the missions requirements. The SWAS satellite provides a three axis stabilized platform to survey a variety of galactic cloud structures. This system includes highly reliable, lightweight launch latch, deployment, and lock mechanisms, and solar array panels that provide the maximum solar cell area. The design of the solar arrays are the result of system trades that included instrument and spacecraft thermal constraints, attitude control system maneuvering rates and pointing accuracies, the power system, and the spacecraft structure.

  5. 3-dimensional current collection model. [of Tethered Satellite System 1

    Science.gov (United States)

    Hwang, Kai-Shen; Shiah, A.; Wu, S. T.; Stone, N.

    1992-01-01

    A three-dimensional, time dependent current collection model of a satellite has been developed for the TSS-1 system. The system has been simulated particularly for the Research of Plasma Electrodynamics (ROPE) experiment. The Maxwellian distributed particles with the geomagnetic field effects are applied in this numerical simulation. The preliminary results indicate that a ring current is observed surrounding the satellite in the equatorial plane. This ring current is found between the plasma sheath and the satellite surface and is oscillating with a time scale of approximately 1 microsec. This is equivalent to the electron plasma frequency. An hour glass shape of electron distribution was observed when the viewing direction is perpendicular to the equatorial plane. This result is consistent with previous findings from Linson (1969) and Antoniades et al. (1990). Electrons that are absorbed by the satellite are limited from the background ionosphere as indicated by Parker and Murphy (1967).

  6. Information content in reflected global navigation satellite system signals

    DEFF Research Database (Denmark)

    Høeg, Per; Carlstrom, Anders

    2011-01-01

    The direct signals from satellites in global satellite navigation satellites systems (GNSS) as, GPS, GLONASS and GALILEO, constitute the primary source for positioning, navigation and timing from space. But also the reflected GNSS signals contain an important information content of signal travel...... times and the characteristics of the reflecting surfaces and structure. Ocean reflected signals from GNSS satellite systems reveal the mean height, the significant wave height and the roughness of the ocean. The estimated accuracy of the average surface height can be as low as 10 cm. For low elevations......, the signals reveal the incoherent scatter process at the reflection zone. By using open-loop high-precision GNSS receivers, it is possible to provide the in-phase and quadrature components of the signal at high sample rates, which enables investigation of the spectral signatures of the observations...

  7. Phase control system concepts and simulations. [solar power satellite system

    Science.gov (United States)

    Lindsay, V. C.

    1980-01-01

    A phase control system concept for a solar power satellite is proposed which partitions the system into three major levels. The first level of phase control consists of a reference phase distribution system implemented in the form of phase distribution tree structure. The major purpose of the tree structure is to electronically compensate for the phase shift due to the transition path lengths from the center of the spacetenna to each phase control center located in each subarray. In the reference system, this is accomplished using the master slave returnable timing system technique. The second level of phase control consists of the beam steering and microwave power generating system which houses the power transponders. This transponder consists of a set of phase conjugation multipliers driven by the reference phase distribution system output and the output of a pilot spread spectrum receiver which accepts the received pilot via a diplexer connected to a separate receive horn or the subarray itself. The output of the phase conjugation circuits serve as inputs to the third level of the phase control system. The third level of phase control is associated with maintaining an equal and constant phase shift through the microwave power amplifier devices while minimizing the associated phase noise effects on the generated power beam. This is accomplished by providing a phase locked loop around each high power amplifier.

  8. Hybrid Atom Electrostatic System for Satellite Geodesy

    Science.gov (United States)

    Zahzam, Nassim; Bidel, Yannick; Bresson, Alexandre; Huynh, Phuong-Anh; Liorzou, Françoise; Lebat, Vincent; Foulon, Bernard; Christophe, Bruno

    2017-04-01

    The subject of this poster comes within the framework of new concepts identification and development for future satellite gravity missions, in continuation of previously launched space missions CHAMP, GRACE, GOCE and ongoing and prospective studies like NGGM, GRACE 2 or E-GRASP. We were here more focused on the inertial sensors that complete the payload of such satellites. The clearly identified instruments for space accelerometry are based on the electrostatic technology developed for many years by ONERA and that offer a high level of performance and a high degree of maturity for space applications. On the other hand, a new generation of sensors based on cold atom interferometry (AI) is emerging and seems very promising in this context. These atomic instruments have already demonstrated on ground impressive results, especially with the development of state-of-the-art gravimeters, and should reach their full potential only in space, where the microgravity environment allows long interaction times. Each of these two types of instruments presents their own advantages which are, for the electrostatic sensors (ES), their demonstrated short term sensitivity and their high TRL, and for AI, amongst others, the absolute nature of the measurement and therefore no need for calibration processes. These two technologies seem in some aspects very complementary and a hybrid sensor bringing together all their assets could be the opportunity to take a big step in this context of gravity space missions. We present here the first experimental association on ground of an electrostatic accelerometer and an atomic accelerometer and underline the interest of calibrating the ES instrument with the AI. Some technical methods using the ES proof-mass as the Raman Mirror seem very promising to remove rotation effects of the satellite on the AI signal. We propose a roadmap to explore further in details and more rigorously this attractive hybridization scheme in order to assess its potential

  9. Guidance and Control System for a Satellite Constellation

    Science.gov (United States)

    Bryson, Jonathan Lamar; Cox, James; Mays, Paul Richard; Neidhoefer, James Christian; Ephrain, Richard

    2010-01-01

    A distributed guidance and control algorithm was developed for a constellation of satellites. The system repositions satellites as required, regulates satellites to desired orbits, and prevents collisions. 1. Optimal methods are used to compute nominal transfers from orbit to orbit. 2. Satellites are regulated to maintain the desired orbits once the transfers are complete. 3. A simulator is used to predict potential collisions or near-misses. 4. Each satellite computes perturbations to its controls so as to increase any unacceptable distances of nearest approach to other objects. a. The avoidance problem is recast in a distributed and locally-linear form to arrive at a tractable solution. b. Plant matrix values are approximated via simulation at each time step. c. The Linear Quadratic Gaussian (LQG) method is used to compute perturbations to the controls that will result in increased miss distances. 5. Once all danger is passed, the satellites return to their original orbits, all the while avoiding each other as above. 6. The delta-Vs are reasonable. The controller begins maneuvers as soon as practical to minimize delta-V. 7. Despite the inclusion of trajectory simulations within the control loop, the algorithm is sufficiently fast for available satellite computer hardware. 8. The required measurement accuracies are within the capabilities of modern inertial measurement devices and modern positioning devices.

  10. Satellite augmentation of cellular type mobile radio telephone systems

    Science.gov (United States)

    Anderson, Roy E.

    NASA's ATS-6 satellite relayed voice bandwidth communications between five trucks and the trucking company dispatchers as the trucks traveled throughout the north-eastern quarter of the contiguous United States. The experiment, conducted over a seven month period, demonstrated that propagation characteristics are much different for the satellite-mobile links than for terrestrial-mobile links. A properly designed satellite system can provide high quality, reliable voice and data communications except where the vehicle-satellite path is shadowed by a structure or terrain feature. Mobile equipment in the experiment was adapted from commercial mobile radios. The vehicle antennas were 75 cm tall, 2 cm diam. Another experiment proved the feasibility of vehicle position surveillance using active two-way tone-code ranging through ATS-6 to provide one line of position and passive one-way ranging by measuring the time-of-arrival of a signal from an independent satellite. A position fix was printed out at an earth station 1 sec after it sent the interrogation signal to the distant vehicle, a towboat on the Mississippi River. The line of position from ATS-6 was accurate to 0.1 nautical mile using a voice bandwidth ranging signal. The line of position from the NOAA GOES satellite was accurate to 2 miles, using 100 Hz signal bandwidth. If the signal from the independent satellite had the same bandwidth and signal-to-noise ratio as ATS-6, the fixes would have been accurate to about 0.1 nautical mile. A concept study concluded that satellites might be a cost effective augmentation of terrestrial cellular type mobile radio telephone systems. The satellites would serve thinly populated areas where terrestrial systems are not cost effective. In the United States, the satellites would serve about 90% of the land area where 20% of the population resides. A multibeam satellite with many channels in each beam would be compatible with the urban terrestrial systems and together they would

  11. Applications of two-way satellite time and frequency transfer in the BeiDou navigation satellite system

    Science.gov (United States)

    Zhou, ShanShi; Hu, XiaoGong; Liu, Li; Guo, Rui; Zhu, LingFeng; Chang, ZhiQiao; Tang, ChengPan; Gong, XiuQiang; Li, Ran; Yu, Yang

    2016-10-01

    A two-way satellite time and frequency transfer (TWSTFT) device equipped in the BeiDou navigation satellite system (BDS) can calculate clock error between satellite and ground master clock. TWSTFT is a real-time method with high accuracy because most system errors such as orbital error, station position error, and tropospheric and ionospheric delay error can be eliminated by calculating the two-way pseudorange difference. Another method, the multi-satellite precision orbit determination (MPOD) method, can be applied to estimate satellite clock errors. By comparison with MPOD clock estimations, this paper discusses the applications of the BDS TWSTFT clock observations in satellite clock measurement, satellite clock prediction, navigation system time monitor, and satellite clock performance assessment in orbit. The results show that with TWSTFT clock observations, the accuracy of satellite clock prediction is higher than MPOD. Five continuous weeks of comparisons with three international GNSS Service (IGS) analysis centers (ACs) show that the reference time difference between BeiDou time (BDT) and golbal positoning system (GPS) time (GPST) realized IGS ACs is in the tens of nanoseconds. Applying the TWSTFT clock error observations may obtain more accurate satellite clock performance evaluation in the 104 s interval because the accuracy of the MPOD clock estimation is not sufficiently high. By comparing the BDS and GPS satellite clock performance, we found that the BDS clock stability at the 103 s interval is approximately 10-12, which is similar to the GPS IIR.

  12. Improvements and Extensions for Joint Polar Satellite System Algorithms

    Science.gov (United States)

    Grant, K. D.

    2016-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather satellite system: the Joint Polar Satellite System (JPSS). JPSS replaced the afternoon orbit component and ground processing of the old POES system managed by NOAA. JPSS satellites carry sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is the Common Ground System (CGS), and provides command, control, and communications (C3), data processing and product delivery. CGS's data processing capability provides environmental data products (Sensor Data Records (SDRs) and Environmental Data Records (EDRs)) to the NOAA Satellite Operations Facility. The first satellite in the JPSS constellation, S-NPP, was launched in October 2011. The second satellite, JPSS-1, is scheduled for launch in January 2017. During a satellite's calibration and validation (Cal/Val) campaign, numerous algorithm updates occur. Changes identified during Cal/Val become available for implementation into the operational system for both S-NPP and JPSS-1. In addition, new capabilities, such as higher spectral and spatial resolution, will be exercised on JPSS-1. This paper will describe changes to current algorithms and products as a result of S-NPP Cal/Val and related initiatives for improved capabilities. Improvements include Cross Track Infrared Sounder high spectral processing, extended spectral and spatial ranges for Ozone Mapping and Profiler Suite ozone Total Column and Nadir Profiles, and updates to Vegetation Index, Snow Cover, Active Fires, Suspended Matter, and Ocean Color. Updates will include Sea Surface Temperature, Cloud Mask, Cloud Properties, and other improvements.

  13. SOFT project: a new forecasting system based on satellite data

    Science.gov (United States)

    Pascual, Ananda; Orfila, A.; Alvarez, Alberto; Hernandez, E.; Gomis, D.; Barth, Alexander; Tintore, Joaquim

    2002-01-01

    The aim of the SOFT project is to develop a new ocean forecasting system by using a combination of satellite dat, evolutionary programming and numerical ocean models. To achieve this objective two steps are proved: (1) to obtain an accurate ocean forecasting system using genetic algorithms based on satellite data; and (2) to integrate the above new system into existing deterministic numerical models. Evolutionary programming will be employed to build 'intelligent' systems that, learning form the past ocean variability and considering the present ocean state, will be able to infer near future ocean conditions. Validation of the forecast skill will be carried out by comparing the forecasts fields with satellite and in situ observations. Validation with satellite observations will provide the expected errors in the forecasting system. Validation with in situ data will indicate the capabilities of the satellite based forecast information to improve the performance of the numerical ocean models. This later validation will be accomplished considering in situ measurements in a specific oceanographic area at two different periods of time. The first set of observations will be employed to feed the hybrid systems while the second set will be used to validate the hybrid and traditional numerical model results.

  14. The Saturn System's Icy Satellites: New Results from Cassini

    Science.gov (United States)

    Lopes-Gautier, Rosaly M.; Buratti, Bonnie; Hendrix, A. R.

    2008-01-01

    Cassini-Huygens is a multidisciplinary, international planetary mission consisting of an orbiting spacecraft and a probe. The Huygens probe successfully landed on Titan's surface on January 14, 2005, while the orbiter has performed observations of Saturn, its rings, satellites, and magnetosphere since it entered orbit around Saturn on July 1, 2004. The Cassini mission has been prolific in its scientific discoveries about the Saturn system. In this special section, we present new mission results with a focus on the 'icy satellites,' which we define as all Saturn's moons with the exception of Titan. The results included in this section have come out of the Cassini SOST--Satellites Orbiter Science Team--a multi-instrument and multidiscipline group that works together to better understand the icy satellites and their interactions with Saturn and its rings. Other papers included in this issue present ground-based observations and interior modeling of these icy moons.

  15. Spatial Cloud Detection and Retrieval System for Satellite Images

    Directory of Open Access Journals (Sweden)

    Ayman Nasr

    2013-01-01

    Full Text Available In last the decade we witnessed a large increase in data generated by earth observing satellites. Hence, intelligent processing of the huge amount of data received by hundreds of earth receiving stations, with specific satellite image oriented approaches, presents itself as a pressing need. One of the most important steps in earlier stages of satellite image processing is cloud detection. Satellite images having a large percentage of cloud cannot be used in further analysis. While there are many approaches that deal with different semantic meaning, there are rarely approaches that deal specifically with cloud detection and retrieval. In this paper we introduce a novel approach that spatially detect and retrieve clouds in satellite images using their unique properties .Our approach is developed as spatial cloud detection and retrieval system (SCDRS that introduce a complete framework for specific semantic retrieval system. It uses a Query by polygon (QBP paradigm for the content of interest instead of using the more conventional rectangular query by image approach. First, we extract features from the satellite images using multiple tile sizes using spatial and textural properties of cloud regions. Second, we retrieve our tiles using a parametric statistical approach within a multilevel refinement process. Our approach has been experimentally validated against the conventional ones yielding enhanced precision and recall rates in the same time it gives more precise detection of cloud coverage regions.

  16. Dependent surveillance through an experimental satellite data link system

    Science.gov (United States)

    Cobley, G. A.

    The development and testing of an experimental dependent aircraft-surveillance system using a satellite data link is reported. In this system, the aircraft position is determined onboard using GPS or inertial navigation, enclosed in a message block using a data-link system, and transmitted to an Inmarsat GEO communication satellites; the ground station receives and analyzes the data to keep constant track of the aircraft position. The hardware implementation and the results of demonstrations performed on flights from Iowa to Wisconsin and the North Atlantic are discussed, and diagrams and maps are provided.

  17. Radiofrequency testing of satellite segment of simulated 30/20 GHz satellite communications system

    Science.gov (United States)

    Leonard, R. F.; Kerczewski, R.

    1985-01-01

    A laboratory communications system has been developed that can serve as a test bed for the evaluation of advanced microwave (30/20 GHz) components produced under NASA technology programs. The system will ultimately permit the transmission of a stream of high-rate (220 Mbps) digital data from the originating user, through a ground terminal, through a hardware-simulated satellite, to a receiving ground station, to the receiving user. This report contains the results of radiofrequency testing of the satellite portion of that system. Data presented include output spurious responses, attainable signal-to-noise ratios, a baseline power budget, usable frequency bands, phase and amplitude response data for each of the frequency bands, and the effects of power level variation.

  18. Remote Synchronization Experiments for Quasi-Senith Satellite System Using Current Geostationary Satellites

    Directory of Open Access Journals (Sweden)

    Toshiaki Iwata

    2010-01-01

    Full Text Available The remote synchronization system for the onboard crystal oscillator (RESSOX realizes accurate synchronization between an atomic clock at a ground station and the QZSS onboard crystal oscillator, reduces overall cost and satellite power consumption, as well as onboard weight and volume, and is expected to have a longer lifetime than a system with onboard atomic clocks. Since a QZSS does not yet exist, we have been conducting synchronization experiments using geostationary earth orbit satellites (JCSAT-1B or Intelsat-4 to confirm that RESSOX is an excellent system for timing synchronization. JCSAT-1B, the elevation angle of which is 46.5 degrees at our institute, is little affected by tropospheric delay, whereas Intelsat-4, the elevation angle of which is 7.9 degrees, is significantly affected. The experimental setup and the results of uplink experiments and feedback experiments using mainly Intelsat-4 are presented. The results show that synchronization within 10 ns is realized.

  19. The principle of the positioning system based on communication satellites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    It is a long dream to realize the communication and navigation functionality in a satellite system in the world. This paper introduces how to establish the system, a positioning system based on communication satellites called Chinese Area Positioning System (CAPS). Instead of the typical navigation satellites, the communication satellites are configured firstly to transfer navigation signals from ground stations, and can be used to obtain service of the positioning, velocity and time, and to achieve the function of navigation and positioning. Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites, the measur- ing and calculation of transfer time of the signals, the carrier frequency drift in communication satellite signal transfer, how to improve the geometrical configuration of the constellation in the system, and the integration of navigation & communication. Several innovative methods are developed to make the new system have full functions of navigation and communication. Based on the development of crucial techniques and methods, the CAPS demonstration system has been designed and developed. Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E, 110.5°E, 134°E, 142°E and barometric altimetry are used in the CAPS system. The GEO satellites located at 134°E and 142°E are decommissioned GEO (DGEO) satellites. C-band is used as the navigation band. Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted. The ground segment consists of five ground stations; the master station is in Lintong, Xi’an. The ground stations take a lot of responsibilities, including monitor and management of the operation of all system components, determination of the satellite position and prediction of the satellite orbit, accomplishment of the virtual atomic clock

  20. Integration of satellite fire products into MPI Earth System Model

    Science.gov (United States)

    Khlystova, Iryna G.; Kloster, Silvia

    2013-04-01

    Fires are the ubiquitous phenomenon affecting all natural biomes. Since the beginning of the satellite Era, fires are being continuously observed from satellites. The most interesting satellite parameter retrieved from satellite measurements is the burned area. Combined with information on biomass available for burning the burned area can be translated into climate relevant carbon emissions from fires into the atmosphere. In this study we integrate observed burned area into a global vegetation model to derive global fire emissions. Global continuous burned area dataset is provided by the Global Fire Emissions Dataset (GFED). GFED products were obtained from MODIS (and pre-MODIS) satellites and are available for the time period of 14 years (1997-2011). This dataset is widely used, well documented and supported by periodical updates containing new features. We integrate the global burned area product into the land model JSBACH, a part of the Earth-System model developed at the Max Plank Institute for Meteorology. The land model JSBACH simulates land biomass in terms of carbon content. Fire is an important disturbance process in the Earth's carbon cycle and affects mainly the carbon stored in vegetation. In the standard JSBACH version fire is represented by process based algorithms. Using the satellite data as an alternative we are targeting better comparability of modeled carbon emissions with independent satellite measurements of atmospheric composition. The structure of burned vegetation inside of a biome can be described as the balance between woody and herbaceous vegetation. GFED provides in addition to the burned area satellite derived information of the tree cover distribution within the burned area. Using this dataset, we can attribute the burned area to the respective simulated herbaceous or woody biomass within the vegetation model. By testing several extreme cases we evaluate the quantitative impact of vegetation balance between woody and herbaceous

  1. Satellite systems for personal applications concepts and technology

    CERN Document Server

    Richharia, Madhavendra

    2010-01-01

    Presents the concepts, technology, and role of satellite systems in support of personal applications, such as mobile and broadband communications, navigation, television, radio and multimedia broadcasting, safety of life services, etc. This book presents a novel perspective on satellite systems, reflecting the modern personal technology context, and hence a focus on the individual as end-user. The book begins by outlining key generic concepts before discussing techniques adopted in particular application areas; next, it exemplifies these techniques through discussion of state-of-art c

  2. Design and characteristics of a multiband communication satellite antenna system

    Science.gov (United States)

    Ueno, Kenji; Itanami, Takao; Kumazawa, Hiroyuki; Ohtomo, Isao

    1995-04-01

    Feasibility studies on a multiband communication satellite antenna system and the key technologies involved in devising this system are described. The proposed multiband communication satellite utilizes four frequency bands: Ka (30/20 GHz), Ku (14/12 GHz), C (6/4 GHz), and S (2.6/2.5 GHz). It has six beam configurations, three multibeam and three shaped-beam. The following key technologies are presented: (1) a low-loss frequency selective subreflector (FSR) for compact feeds, (2) a low-loss and broadband frequency selective surface (FSS), and (3) a highly accurate and reliable mesh reflector.

  3. Improvement of orbit determination accuracy for Beidou Navigation Satellite System with Two-way Satellite Time Frequency Transfer

    Science.gov (United States)

    Tang, Chengpan; Hu, Xiaogong; Zhou, Shanshi; Guo, Rui; He, Feng; Liu, Li; Zhu, Lingfeng; Li, Xiaojie; Wu, Shan; Zhao, Gang; Yu, Yang; Cao, Yueling

    2016-10-01

    The Beidou Navigation Satellite System (BDS) manages to estimate simultaneously the orbits and clock offsets of navigation satellites, using code and carrier phase measurements of a regional network within China. The satellite clock offsets are also directly measured with Two-way Satellite Time Frequency Transfer (TWSTFT). Satellite laser ranging (SLR) residuals and comparisons with the precise ephemeris indicate that the radial error of GEO satellites is much larger than that of IGSO and MEO satellites and that the BDS orbit accuracy is worse than GPS. In order to improve the orbit determination accuracy for BDS, a new orbit determination strategy is proposed, in which the satellite clock measurements from TWSTFT are fixed as known values, and only the orbits of the satellites are solved. However, a constant systematic error at the nanosecond level can be found in the clock measurements, which is obtained and then corrected by differencing the clock measurements and the clock estimates from orbit determination. The effectiveness of the new strategy is verified by a GPS regional network orbit determination experiment. With the IGS final clock products fixed, the orbit determination and prediction accuracy for GPS satellites improve by more than 50% and the 12-h prediction User Range Error (URE) is better than 0.12 m. By processing a 25-day of measurement from the BDS regional network, an optimal strategy for the satellite-clock-fixed orbit determination is identified. User Equivalent Ranging Error is reduced by 27.6% for GEO satellites, but no apparent reduction is found for IGSO/MEO satellites. The SLR residuals exhibit reductions by 59% and 32% for IGSO satellites but no reductions for GEO and MEO satellites.

  4. Satellite-aided mobile radio concepts study: Concept definition of a satellite-aided mobile and personal radio communication system

    Science.gov (United States)

    Anderson, R. E.

    1979-01-01

    The satellite system requires the use of a large satellite antenna and spacecraft array power of about 12 kW or more depending on the operating frequency. Technology developments needed include large offset reflector multibeam antennas, satellite electrical power sybsystems providing greater than 12 kW of power, signal switching hardware, and linearized efficient solid state amplifiers for the satellite-aided mobile band. Presently there is no frequency assignment for this service, and it is recommended that an allocation be pursued. The satellite system appears to be within reasonable extrapolation of the state of the art. It is further recommended that the satellite-aided system spacecraft definition studies and supporting technology development be initiated.

  5. The principle of the positioning system based on communication satellites

    Institute of Scientific and Technical Information of China (English)

    AI GuoXiang; SHI HuLi; WU HaiTao; LI ZhiGang; GUO Ji

    2009-01-01

    It is a long dream to realize the communication and navigation functionality in a satellite system in the world.This paper introduces how to establish the system,a positioning system based on communication satellites called Chinese Area Positioning System (CAPS).Instead of the typical navigation satelIites,the communication satellites are configured firstly to transfer navigation signals from ground stations,and can be used to obtain service of the positioning,velocity and time,and to achieve the function of navigation and positioning.Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites,the measuring and calculation of transfer time of the signals,the carrier frequency drift in communication satellite ignal transfer,how to improve the geometrical configuration of the constellation in the system,and the integration of navigation & communication.Several innovative methods are developed to make the new system have full functions of navigation and communication.Based on the development of crucial techniques and methods,the CAPS demonstration system has been designed and developed.Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E,110.5°E,134°E,142°E and barometric altimetry are used in the CAPS system.The GEO satellites located at 134°E and 142°E re decommissioned GEO (DGEO) satellites.C-band is used as the navigation band.Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted.The ground segment consists of five ground stations; the master station is in Lintong,Xi'an.The ground stations take a lot of responsibilities,including monitor and management of the operation of all system components,determination of the satellite position and prediction of the satellite orbit,accomplishment of the virtual atomic clock measurement,transmission and receiving

  6. An Orbiting Standards Platform for communication satellite system RF measurements

    Science.gov (United States)

    Wallace, R. G.; Woodruff, J. J.

    1978-01-01

    The Orbiting Standards Platform (OSP) is a proposed satellite dedicated to performing RF measurements on space communications systems. It would consist of a quasi-geostationary spacecraft containing an ensemble of calibrated RF sources and field strength meters operating in several microwave bands, and would be capable of accurately and conveniently measuring critical earth station and satellite RF performance parameters, such as EIRP, gain, figure of merit (G/T), crosspolarization, beamwidth, and sidelobe levels. The feasibility and utility of the OSP concept has been under joint study by NASA, NBS, Comsat and NTIA. A survey of potential OSP users was conducted by NTIA as part of this effort. The response to this survey, along with certain trends in satellite communications system design, indicates a growing need for such a measurement service.

  7. Testing a satellite automatic nutation control system. [on synchronous meteorological satellite

    Science.gov (United States)

    Hrasiar, J. A.

    1974-01-01

    Testing of a particular nutation control system for the synchronous meteorological satellite (SMS) is described. The test method and principles are applicable to nutation angle control for other satellites with similar requirements. During its ascent to synchronous orbit, a spacecraft like the SMS spins about its minimum-moment-of-inertia axis. An uncontrolled spacecraft in this state is unstable because torques due to fuel motion increase the nutation angle. However, the SMS is equipped with an automatic nutation control (ANC) system which will keep the nutation angle close to zero. Because correct operation of this system is critical to mission success, it was tested on an air-bearing table. The ANC system was mounted on the three-axis air-bearing table which was scaled to the SMS and equipped with appropriate sensors and thrusters. The table was spun up in an altitude chamber and nutation induced so that table motion simulated spacecraft motion. The ANC system was used to reduce the nutation angle. This dynamic test of the ANC system met all its objectives and provided confidence that the ANC system will control the SMS nutation angle.

  8. Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems

    OpenAIRE

    Sasaki, Takanori; Stewart, Glen R.; Ida, Shigeru

    2010-01-01

    The Jovian regular satellite system mainly consists of four Galilean satellites that have similar masses and are trapped in mutual mean motion resonances except for the outer satellite, Callisto. On the other hand, the Saturnian regular satellite system has only one big icy body, Titan, and a population of much smaller icy moons. We have investigated the origin of these major differences between the Jovian and Saturnian satellite systems by semi-analytically simulating the growth and orbital ...

  9. Multi-agent robotic systems and applications for satellite missions

    Science.gov (United States)

    Nunes, Miguel A.

    A revolution in the space sector is happening. It is expected that in the next decade there will be more satellites launched than in the previous sixty years of space exploration. Major challenges are associated with this growth of space assets such as the autonomy and management of large groups of satellites, in particular with small satellites. There are two main objectives for this work. First, a flexible and distributed software architecture is presented to expand the possibilities of spacecraft autonomy and in particular autonomous motion in attitude and position. The approach taken is based on the concept of distributed software agents, also referred to as multi-agent robotic system. Agents are defined as software programs that are social, reactive and proactive to autonomously maximize the chances of achieving the set goals. Part of the work is to demonstrate that a multi-agent robotic system is a feasible approach for different problems of autonomy such as satellite attitude determination and control and autonomous rendezvous and docking. The second main objective is to develop a method to optimize multi-satellite configurations in space, also known as satellite constellations. This automated method generates new optimal mega-constellations designs for Earth observations and fast revisit times on large ground areas. The optimal satellite constellation can be used by researchers as the baseline for new missions. The first contribution of this work is the development of a new multi-agent robotic system for distributing the attitude determination and control subsystem for HiakaSat. The multi-agent robotic system is implemented and tested on the satellite hardware-in-the-loop testbed that simulates a representative space environment. The results show that the newly proposed system for this particular case achieves an equivalent control performance when compared to the monolithic implementation. In terms on computational efficiency it is found that the multi

  10. The international maritime satellite communications system INMARSAT (Handbook)

    Science.gov (United States)

    Zhilin, Viktor A.

    The organization and services provided by the INMARSAT satellite communications system are summarized. The structure and operation of the system are described with reference to transmission line parameters, frequency assignment, signals, telex communications, electrical parameters of communication channels, modulation, synchronization, and methods of protection against errors in the transmission of discrete messages. The discussion also covers the principal components of the INMARSAT system and the operation of ship-based stations.

  11. A Fault tolerant Control Supervisory System development Procedurefor Small Satellites

    DEFF Research Database (Denmark)

    Izadi-Zamanabadi, Roozbeh; Larsen, Jesper Abildgaard

    The paper presents a stepwise procedure to develop a fault tolerant control system for small satellites. The procedure is illustrated through implementation on the AAUSAT-II spacecraft. As it is shown the presented procedure requires expertise from several disciplines that are nevertheless...

  12. Internal Calibration of HJ-1-C Satellite SAR System

    Directory of Open Access Journals (Sweden)

    Yang Zhen

    2014-06-01

    Full Text Available The HJ-1-C satellite is a Synthetic Aperture Radar (SAR satellite of a small constellation for environmental and disaster monitoring. At present, it is in orbit and working well. The SAR system uses a mesh reflector antenna and centralized power amplifier, and has an internal calibration function in orbit. This study introduces the internal calibration modes and signal paths. The design and realization of the internal calibrator are discussed in detail. Finally, the internal calibration data acquired in orbit are also analyzed.

  13. Multi-spectral band selection for satellite-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Clodius, W.B.; Weber, P.G.; Borel, C.C.; Smith, B.W.

    1998-09-01

    The design of satellite based multispectral imaging systems requires the consideration of a number of tradeoffs between cost and performance. The authors have recently been involved in the design and evaluation of a satellite based multispectral sensor operating from the visible through the long wavelength IR. The criteria that led to some of the proposed designs and the modeling used to evaluate and fine tune the designs will both be discussed. These criteria emphasized the use of bands for surface temperature retrieval and the correction of atmospheric effects. The impact of cost estimate changes on the final design will also be discussed.

  14. Search and rescue satellite-aided tracking system

    Science.gov (United States)

    Trudell, B.; Gutwein, J. M.; Vollmers, R.; Wammer, D.

    1980-10-01

    The objective of Sarsat is to demonstrate that satellites can greatly facilitate the monitoring, detection, and location of distress incidents alerted by Emergency Locator Transmitters (ELTs) and Emergency Position Indicating Radio Beacons (EPIRBs) carried on commercial, military, and general aviation aircraft and some marine vessels. The detection and location will be accomplished by relaying, via satellite, ELT/EPIRB distress information to ground stations, which will complete the data processing and forward alert and position location data to rescue coordination services. This paper presents a Sarsat system description and a summary of Coast Guard and USAF objectives for the initial demonstration and evaluation tests of Sarsat.

  15. An interactive system for compositing digital radar and satellite data

    Science.gov (United States)

    Heymsfield, G. M.; Ghosh, K. K.; Chen, L. C.

    1983-01-01

    This paper describes an approach for compositing digital radar data and GOES satellite data for meteorological analysis. The processing is performed on a user-oriented image processing system, and is designed to be used in the research mode. It has a capability to construct PPIs and three-dimensional CAPPIs using conventional as well as Doppler data, and to composite other types of data. In the remapping of radar data to satellite coordinates, two steps are necessary. First, PPI or CAPPI images are remapped onto a latitude-longitude projection. Then, the radar data are projected into satellite coordinates. The exact spherical trigonometric equations, and the approximations derived for simplifying the computations are given. The use of these approximations appears justified for most meteorological applications. The largest errors in the remapping procedure result from the satellite viewing angle parallax, which varies according to the cloud top height. The horizontal positional error due to this is of the order of the error in the assumed cloud height in mid-latitudes. Examples of PPI and CAPPI data composited with satellite data are given for Hurricane Frederic on 13 September 1979 and for a squall line on 2 May 1979 in Oklahoma.

  16. Sensor system for Greenhouse Gas Observing Satellite (GOSAT)

    Science.gov (United States)

    Hamazaki, Takashi; Kuze, Akihiko; Kondo, Kayoko

    2004-11-01

    Global warming has become a very serious issue for human beings. In 1997, the Kyoto Protocol was adopted at the Third Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP3), making it mandatory for developed nations to reduce carbon dioxide emissions by six (6) to eight (8) per cent of their total emissions in 1990, and to meet this goal sometime between 2008 and 2012. The Greenhouse gases Observing SATellite (GOSAT) is design to monitor the global distribution of carbon dioxide (CO2) from orbit. GOSAT is a joint project of Japan Aerospace Exploration Agency (JAXA), the Ministry of Environment (MOE), and the National Institute for Environmental Studies (NIES). JAXA is responsible for the satellite and instrument development, MOE is involved in the instrument development, and NIES is responsible for the satellite data retrieval. The satellite is scheduled to be launched in 2008. In order to detect the CO2 variation of boundary layers, both the technique to measure the column density and the retrieval algorithm to remove cloud and aerosol contamination are investigated. Main mission sensor of the GOSAT is a Fourier Transform Spectrometer with high optical throughput, spectral resolution and wide spectral coverage, and a cloud-aerosol detecting imager attached to the satellite. The paper presents the mission sensor system of the GOSAT together with the results of performance demonstration with proto-type instrument aboard an aircraft.

  17. Accuracy Performance Evaluation of Beidou Navigation Satellite System

    Science.gov (United States)

    Wang, W.; Hu, Y. N.

    2017-03-01

    Accuracy is one of the key elements of the regional Beidou Navigation Satellite System (BDS) performance standard. In this paper, we review the definition specification and evaluation standard of the BDS accuracy. Current accuracy of the regional BDS is analyzed through the ground measurements and compared with GPS in terms of dilution of precision (DOP), signal-in-space user range error (SIS URE), and positioning accuracy. The Positioning DOP (PDOP) map of BDS around Chinese mainland is compared with that of GPS. The GPS PDOP is between 1.0-2.0 and does not vary with the user latitude and longitude, while the BDS PDOP varies between 1.5-5.0, and increases as the user latitude increases, and as the user longitude apart from 118°. The accuracies of the broadcast orbits of BDS are assessed by taking the precise orbits from International GNSS Service (IGS) as the reference, and by making satellite laser ranging (SLR) residuals. The radial errors of the BDS inclined geosynchronous orbit (IGSO) and medium orbit (MEO) satellites broadcast orbits are at the 0.5m level, which are larger than those of GPS satellites at the 0.2m level. The SLR residuals of geosynchronous orbit (GEO) satellites are 65.0cm, which are larger than those of IGSO, and MEO satellites, at the 50.0cm level. The accuracy of broadcast clock offset parameters of BDS is computed by taking the clock measurements of Two-way Satellite Radio Time Frequency Transfer as the reference. Affected by the age of broadcast clock parameters, the error of the broadcast clock offset parameters of the MEO satellites is the largest, at the 0.80m level. Finally, measurements of the multi-GNSS (MGEX) receivers are used for positioning accuracy assessment of BDS and GPS. It is concluded that the positioning accuracy of regional BDS is better than 10m at the horizontal component and the vertical component. The combined positioning accuracy of both systems is better than one specific system.

  18. A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking

    Science.gov (United States)

    Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)

    1995-01-01

    A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

  19. Satellite-Tracking Millimeter-Wave Reflector Antenna System For Mobile Satellite-Tracking

    Science.gov (United States)

    Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)

    2001-01-01

    A miniature dual-band two-way mobile satellite-tracking antenna system mounted on a movable vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

  20. Cyber security with radio frequency interferences mitigation study for satellite systems

    Science.gov (United States)

    Wang, Gang; Wei, Sixiao; Chen, Genshe; Tian, Xin; Shen, Dan; Pham, Khanh; Nguyen, Tien M.; Blasch, Erik

    2016-05-01

    Satellite systems including the Global Navigation Satellite System (GNSS) and the satellite communications (SATCOM) system provide great convenience and utility to human life including emergency response, wide area efficient communications, and effective transportation. Elements of satellite systems incorporate technologies such as navigation with the global positioning system (GPS), satellite digital video broadcasting, and information transmission with a very small aperture terminal (VSAT), etc. The satellite systems importance is growing in prominence with end users' requirement for globally high data rate transmissions; the cost reduction of launching satellites; development of smaller sized satellites including cubesat, nanosat, picosat, and femtosat; and integrating internet services with satellite networks. However, with the promising benefits, challenges remain to fully develop secure and robust satellite systems with pervasive computing and communications. In this paper, we investigate both cyber security and radio frequency (RF) interferences mitigation for satellite systems, and demonstrate that they are not isolated. The action space for both cyber security and RF interferences are firstly summarized for satellite systems, based on which the mitigation schemes for both cyber security and RF interferences are given. A multi-layered satellite systems structure is provided with cross-layer design considering multi-path routing and channel coding, to provide great security and diversity gains for secure and robust satellite systems.

  1. Mobile satellite news gathering (SNG) system; Soko SNG (Satellite News Gathering) shasaikyoku

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Commercialization was made for broadcasting stations on a mobile station system capable of capturing a satellite automatically while the system is moving. Its feature is the enhanced tracking accuracy as a result of using the Company's original null-sensor (see Note), and detecting and controlling intersecting polarized waves of reference signals from the satellite. The material for transmission is digitally transmitted by MPEG2, making it possible to transmit more data than by conventional systems. The system is being used for live broadcasting of marathon races and emergency news broadcasting. It is expected that the system may be applied to applications other than broadcasting stations, such as automobiles and ships. (Note: A null-sensor is a unit used for adjusting antenna directions for an SNG transmitter. It uses IF receiving signals of H/V polarized waves of parabolic antenna as an input, and outputs the main polarized wave level and the intersecting polarized wave level.) (translated by NEDO)

  2. Satellite Power Systems (SPS) concept definition study. Volume 5: Special emphasis studies. [rectenna and solar power satellite design studies

    Science.gov (United States)

    Hanley, G. M.

    1980-01-01

    Satellite configurations based on the Satellite Power System baseline requirements were analyzed and a preferred concept selected. A satellite construction base was defined, precursor operations incident to establishment of orbital support facilities identified, and the satellite construction sequence and procedures developed. Rectenna construction requirement were also addressed. Mass flow to orbit requirements were revised and traffic models established based on construction of 60 instead of 120 satellites. Analyses were conducted to determine satellite control, resources, manufacturing, and propellant requirements. The impact of the laser beam used for space-to-Earth power transmission upon the intervening atmosphere was examined as well as the inverse effect. The significant space environments and their effects on spacecraft components were investigated to define the design and operational limits imposed by the environments on an orbit transfer vehicle. The results show that LEO altitude 300 nmi and transfer orbit duration 6 months are preferrable.

  3. The MUSES Satellite Team and Multidisciplinary System Engineering

    Science.gov (United States)

    Chen, John C.; Paiz, Alfred R.; Young, Donald L.

    1997-01-01

    In a unique partnership between three minority-serving institutions and NASA's Jet Propulsion Laboratory, a new course sequence, including a multidisciplinary capstone design experience, is to be developed and implemented at each of the schools with the ambitious goal of designing, constructing and launching a low-orbit Earth-resources satellite. The three universities involved are North Carolina A&T State University (NCA&T), University of Texas, El Paso (UTEP), and California State University, Los Angeles (CSULA). The schools form a consortium collectively known as MUSES - Minority Universities System Engineering and Satellite. Four aspects of this project make it unique: (1) Including all engineering disciplines in the capstone design course, (2) designing, building and launching an Earth-resources satellite, (3) sustaining the partnership between the three schools to achieve this goal, and (4) implementing systems engineering pedagogy at each of the three schools. This paper will describe the partnership and its goals, the first design of the satellite, the courses developed at NCA&T, and the implementation plan for the course sequence.

  4. Satellite Imagery Assisted Road-Based Visual Navigation System

    Science.gov (United States)

    Volkova, A.; Gibbens, P. W.

    2016-06-01

    There is a growing demand for unmanned aerial systems as autonomous surveillance, exploration and remote sensing solutions. Among the key concerns for robust operation of these systems is the need to reliably navigate the environment without reliance on global navigation satellite system (GNSS). This is of particular concern in Defence circles, but is also a major safety issue for commercial operations. In these circumstances, the aircraft needs to navigate relying only on information from on-board passive sensors such as digital cameras. An autonomous feature-based visual system presented in this work offers a novel integral approach to the modelling and registration of visual features that responds to the specific needs of the navigation system. It detects visual features from Google Earth* build a feature database. The same algorithm then detects features in an on-board cameras video stream. On one level this serves to localise the vehicle relative to the environment using Simultaneous Localisation and Mapping (SLAM). On a second level it correlates them with the database to localise the vehicle with respect to the inertial frame. The performance of the presented visual navigation system was compared using the satellite imagery from different years. Based on comparison results, an analysis of the effects of seasonal, structural and qualitative changes of the imagery source on the performance of the navigation algorithm is presented. * The algorithm is independent of the source of satellite imagery and another provider can be used

  5. Interoperability of satellite-based augmentation systems for aircraft navigation

    Science.gov (United States)

    Dai, Donghai

    The Federal Aviation Administration (FAA) is pioneering a transformation of the national airspace system from its present ground based navigation and landing systems to a satellite based system using the Global Positioning System (GPS). To meet the critical safety-of-life aviation positioning requirements, a Satellite-Based Augmentation System (SBAS), the Wide Area Augmentation System (WAAS), is being implemented to support navigation for all phases of flight, including Category I precision approach. The system is designed to be used as a primary means of navigation, capable of meeting the Required Navigation Performance (RNP), and therefore must satisfy the accuracy, integrity, continuity and availability requirements. In recent years there has been international acceptance of Global Navigation Satellite Systems (GNSS), spurring widespread growth in the independent development of SBASs. Besides the FAA's WAAS, the European Geostationary Navigation Overlay Service System (EGNOS) and the Japan Civil Aviation Bureau's MTSAT-Satellite Augmentation System (MSAS) are also being actively developed. Although all of these SBASs can operate as stand-alone, regional systems, there is increasing interest in linking these SBASs together to reduce costs while improving service coverage. This research investigated the coverage and availability improvements due to cooperative efforts among regional SBAS networks. The primary goal was to identify the optimal interoperation strategies in terms of performance, complexity and practicality. The core algorithms associated with the most promising concepts were developed and demonstrated. Experimental verification of the most promising concepts was conducted using data collected from a joint international test between the National Satellite Test Bed (NSTB) and the EGNOS System Test Bed (ESTB). This research clearly shows that a simple switch between SBASs made by the airborne equipment is the most effective choice for achieving the

  6. Automatic charge control system for satellites

    Science.gov (United States)

    Shuman, B. M.; Cohen, H. A.

    1985-01-01

    The SCATHA and the ATS-5 and 6 spacecraft provided insights to the problem of spacecraft charging at geosychronous altitudes. Reduction of the levels of both absolute and differential charging was indicated, by the emission of low energy neutral plasma. It is appropriate to complete the transition from experimental results to the development of a system that will sense the state-of-charge of a spacecraft, and, when a predetermined threshold is reached, will respond automatically to reduce it. A development program was initiated utilizing sensors comparable to the proton electrostatic analyzer, the surface potential monitor, and the transient pulse monitor that flew in SCATHA, and combine these outputs through a microprocessor controller to operate a rapid-start, low energy plasma source.

  7. A Reusable Software Architecture for Small Satellite AOCS Systems

    DEFF Research Database (Denmark)

    Alminde, Lars; Bendtsen, Jan Dimon; Laursen, Karl Kaas

    2006-01-01

    with both hardware and on-board software. Some of the key issues addressed by the framework are automatic translation of mathematical specifications of hybrid systems into executable software entities, management of execution of coupled models in a parallel distributed environment, as well as interaction......This paper concerns the software architecture called Sophy, which is an abbreviation for Simulation, Observation, and Planning in HYbrid systems. We present a framework that allows execution of hybrid dynamical systems in an on-line distributed computing environment, which includes interaction...... with external components, hardware and/or software, through generic interfaces. Sophy is primarily intended as a tool for development of model based reusable software for the control and autonomous functions of satellites and/or satellite clusters....

  8. Gravimetry, Relativity, and the Global Navigation Satellite Systems

    CERN Document Server

    Tarantola, Albert; Pozo, Jose Maria; Coll, Bartolome

    2009-01-01

    Relativity is an integral part of positioning systems, and this is taken into account in today's practice by applying many "relativistic corrections" to computations performed using concepts borrowed from Galilean physics. A different, fully relativistic paradigm can be developed for operating a positioning system. This implies some fundamental changes. For instance, the basic coordinates are four times (with a symmetric meaning, not three space coordinate and one time coordinate) and the satellites must have cross-link capabilities. Gravitation must, of course, be taken into account, but not using the Newtonian theory: the gravitation field is, and only is, the space-time metric. This implies that the positioning problem and the gravimetry problem can not be separated. An optimization theory can be developed that, because it is fully relativistic, does not contain any "relativistic correction". We suggest that all positioning satellite systems should be operated in this way. The first benefit of doing so wou...

  9. Analysis of satellite broadcasting systems for digital television

    Science.gov (United States)

    de Gaudenzi, Riccardo; Elia, Carlo; Viola, Roberto

    1993-01-01

    This paper introduces the new concept of digital direct satellite broadcasting (D-DBS), which allows unprecedented flexibility by providing a large number of audio-visual services. The concept elaborated on in this paper assumes an information rate of about 40 Mb/s, which is compatible with practically all present-day transponders. After discussion of the general system concept, the optimization procedure is introduced and results of the transmission system optimization are presented. Channel distortion and uplink/downlink interference effects are taken into account by means of a time domain system computer simulation approach. It is shown, by means of link budget analysis, how a medium power direct-to-home TV satellite can provide multimedia services to users equipped with small (60 cm) dish antennas.

  10. An active attitude control system for a drag sail satellite

    Science.gov (United States)

    Steyn, Willem Herman; Jordaan, Hendrik Willem

    2016-11-01

    The paper describes the development and simulation results of a full ADCS subsystem for the deOrbitSail drag sail mission. The deOrbitSail satellite was developed as part of an European FP7 collaboration research project. The satellite was launched and commissioning started on 10th July 2015. Various new actuators and sensors designed for this mission will be presented. The deOrbitSail satellite is a 3U CubeSat to deploy a 4 by 4 m drag sail from an initial 650 km circular polar low earth orbit. With an active attitude control system it will be shown that by maximising the drag force, the expected de-orbiting period from the initial altitude will be less than 50 days. A future application of this technology will be the use of small drag sails as low-cost devices to de-orbit LEO satellites, when they have reached their end of life, without having to use expensive propulsion systems. Simulation and Hardware-in-Loop experiments proved the feasibility of the proposed attitude control system. A magnetic-only control approach using a Y-Thomson spin, is used to detumble the 3U Cubesat with stowed sail and subsequently to 3-axis stabilise the satellite to be ready for the final deployment phase. Minituarised torquer rods, a nano-sized momentum wheel, attitude sensor hardware (magnetometer, sun, earth) developed for this phase will be presented. The final phase will be to deploy and 3-axis stabilise the drag sail normal to the satellite's velocity vector, using a combined Y-momentum wheel and magnetic controller. The design and performance improvements when using a 2-axis translation stage to adjust the sail centre-of-pressure to satellite centre-of-mass offset, will also be discussed, although for launch risk reasons this stage was not included in the final flight configuration. To accurately determine the drag sail's attitude during the sunlit part of the orbit, an accurate wide field of view dual sensor to measure both the sun and nadir vector direction was developed for

  11. Space Weathering on Icy Satellites in the Outer Solar System

    Science.gov (United States)

    Clark, R. N.; Perlman, Z.; Pearson, N.; Cruikshank, D. P.

    2014-01-01

    Space weathering produces well-known optical effects in silicate minerals in the inner Solar System, for example, on the Moon. Space weathering from solar wind and UV (ultraviolet radiation) is expected to be significantly weaker in the outer Solar System simply because intensities are low. However, cosmic rays and micrometeoroid bombardment would be similar to first order. That, combined with the much higher volatility of icy surfaces means there is the potential for space weathering on icy outer Solar System surfaces to show optical effects. The Cassini spacecraft orbiting Saturn is providing evidence for space weathering on icy bodies. The Cassini Visible and Infrared Mapping Spectrometer (VIMS) instrument has spatially mapped satellite surfaces and the rings from 0.35-5 microns and the Ultraviolet Imaging Spectrograph (UVIS) instrument from 0.1 to 0.2 microns. These data have sampled a complex mixing space between H2O ice and non-ice components and they show some common spectral properties. Similarly, spectra of the icy Galilean satellites and satellites in the Uranian system have some commonality in spectral properties with those in the Saturn system. The UV absorber is spectrally similar on many surfaces. VIMS has identified CO2, H2 and trace organics in varying abundances on Saturn's satellites. We postulate that through the spatial relationships of some of these compounds that they are created and destroyed through space weathering effects. For example, the trapped H2 and CO2 observed by VIMS in regions with high concentrations of dark material may in part be space weathering products from the destruction of H2O and organic molecules. The dark material, particularly on Iapetus which has the highest concentration in the Saturn system, is well matched by space-weathered silicates in the .4 to 2.6 micron range, and the spectral shapes closely match those of the most mature lunar soils, another indicator of space weathered material.

  12. The European Satellite Navigation System Galileo

    Institute of Scientific and Technical Information of China (English)

    G.W. Hein; T. Pany

    2003-01-01

    This paper starts with a brief discussion of the Galileo project status and with a description of the present Galileo architecture (space segment, ground segment, user segment). It focuses on explaining special features compared to the American GPS system. The presentation of the user segment comprises a discussion of the actual Galileo signal structure. The Galileo carrier frequency, modulation scheme and data rate of all 10 navigation signals are described as well as parameters of the search and rescue service. The navigation signals are used to realize three types of open services, the safety of life service, two types of commercial services and the public regulated service. The signal performance in terms of the pseudorange code error due to thermal noise and multipath is discussed as well as interference to and from other radionavigation services broadcasting in the E5 and E6 frequency band. The interoperability and compatibility of Galileo and GPS is realized by a properly chosen signal structures in E5a/L5 and E2-L1-E1 and compatible geodetic and time reference frames. Some new results on reciprocal GPS/Galileo signal degradation due to signal overlay are presented as well as basic requirements on the Galileo code sequences.

  13. Autonomous Attitude Determination and Control System for the Ørsted Satellite

    DEFF Research Database (Denmark)

    Bak, Thomas; Wisniewski, Rafal; Blanke, M.

    1996-01-01

    The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system.......The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system....

  14. Personal Access Satellite System (PASS) study. Fiscal year 1989 results

    Science.gov (United States)

    Sue, Miles K. (Editor)

    1990-01-01

    The Jet Propulsion Laboratory is exploring the potential and feasibility of a personal access satellite system (PASS) that will offer the user greater freedom and mobility than existing or currently planned communications systems. Studies performed in prior years resulted in a strawman design and the identification of technologies that are critical to the successful implementation of PASS. The study efforts in FY-89 were directed towards alternative design options with the objective of either improving the system performance or alleviating the constraints on the user terminal. The various design options and system issues studied this year and the results of the study are presented.

  15. Advanced Microelectronics Technologies for Future Small Satellite Systems

    Science.gov (United States)

    Alkalai, Leon

    1999-01-01

    Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Whereas these technological advances are being fueled by the commercial (non-space) industries, more recently there has been an exciting new synergism evolving between the two otherwise disjointed markets. In other words, both the commercial and space industries are enabled by advances in low-power, highly integrated, miniaturized (low-volume), lightweight, and reliable real-time embedded systems. Recent announcements by commercial semiconductor manufacturers to introduce Silicon On Insulator (SOI) technology into their commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications. In this paper, we describe the advanced microelectronics and avionics technologies under development by NASA's Deep Space Systems Technology Program (also known as X2000). These technologies are of significant benefit to both the commercial satellite as well as the deep-space and Earth orbiting science missions. Such a synergistic technology roadmap may truly enable quick turn-around, low-cost, and highly capable small satellite systems for both Earth observation as well as deep-space missions.

  16. Satellite Power Systems (SPS) concept definition study. Volume 4: SPS point design definition

    Science.gov (United States)

    Hanley, G.

    1978-01-01

    The satellite power systems point design concept is described. The concept definition includes satellite, ground and space systems, and their relationships. Emphasis is placed on the definition of the GaAlAs photovoltaic satellite system. The major subsystems of the satellite system including power conversion, power distribution and control, microwave, attitude control and stationkeeping, thermal control, structures, and information management and control are discussed.

  17. Concept of an Effective Sentinel-1 Satellite SAR Interferometry System

    OpenAIRE

    2016-01-01

    This brief study introduces a partially working concept being developed at IT4Innovations supercomputer (HPC) facility. This concept consists of several modules that form a whole body of an efficient system for observation of terrain or objects displacements using satellite SAR interferometry (InSAR). A metadata database helps to locate data stored in various storages and to perform basic analyzes. A special database has been designed to describe Sentinel-1 data, on its burst level. Custom Se...

  18. System analysis for millimeter-wave communication satellites

    Science.gov (United States)

    Holland, L. D.; Hilsen, N. B.; Gallagher, J. J.; Stevens, G.

    1980-01-01

    Research and development needs for millimeter-wave space communication systems are presented. Assumed propagation fade statistics are investigated along with high data rate diversity link and storage. The development of reliable ferrite switches, and high performance receivers and transmitters is discussed, in addition to improved tolerance of dish and lens fabrication for the antennas. The typical cost for using a simplex voice channel via a high capacity 40/50 GHz satellite is presented.

  19. Management approach recommendations. Earth Observatory Satellite system definition study (EOS)

    Science.gov (United States)

    1974-01-01

    Management analyses and tradeoffs were performed to determine the most cost effective management approach for the Earth Observatory Satellite (EOS) Phase C/D. The basic objectives of the management approach are identified. Some of the subjects considered are as follows: (1) contract startup phase, (2) project management control system, (3) configuration management, (4) quality control and reliability engineering requirements, and (5) the parts procurement program.

  20. 77 FR 58579 - Certain Two-Way Global Satellite Communication Devices, System and Components Thereof...

    Science.gov (United States)

    2012-09-21

    ... COMMISSION Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Institution...-way global satellite communication devices, system and components thereof by reason of infringement of... after importation of certain two-way global satellite communication devices, system and components...

  1. 78 FR 31576 - Enforcement Proceeding; Certain Two-Way Global Satellite Communication Devices, System and...

    Science.gov (United States)

    2013-05-24

    ... Proceeding; Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Notice of... United States after importation of certain two-way global satellite communication devices, system and... States after importation any two-way global satellite communication devices, system, and components...

  2. A preliminary design for a satellite power system

    Science.gov (United States)

    Enriquez, Clara V.; Kokaly, Ray; Nandi, Saumya; Timmons, Mike; Garrard, Mark; Mercado, Rommel; Rogers, Brian; Ugaz, Victor

    1991-01-01

    Outlined here is a preliminary design for a Solar Power Satellite (SPS) system. The SPS will provide a clean, reliable source of energy for mass consumption. The system will use satellites in geostationary orbits around the Earth to capture the sun's energy. The intercepted sunlight will be converted to laser beam energy which can be transmitted to the Earth's surface. Ground systems on the Earth will convert the transmissions from space into electric power. The preliminary design for the SPS consists of one satellite in orbit around the Earth transmitting to one ground station. The SPs technology uses multi-layer solar cell technology arranged on a 20 sq km planar array to intercept sunlight and convert it to an electric voltage. Power conditioning devices then send the electricity to a laser, which transmits the power to the surface of the Earth. A ground station will convert the beam into electricity. Construction will take place in low Earth orbit and array sections, 20 in total, will be sailed on the solar wind out to the GEO location in 150 days. These individual transportation sections are referred to as solar sailing panels (SSAPs). The primary truss elements used to support the arrays are composed on composite tubular members in a pentahedral arrangement. Smart segments consisting of passive and active damping devices will increase the control of dynamic SPS modes.

  3. Present and Future Trends in Military Satellite Communication Systems

    Directory of Open Access Journals (Sweden)

    C.K. Chatterjee

    1993-01-01

    Full Text Available Recent years have seen a phenomenal growth in the field of satellite communications. Satcom systems offer many advantages for military applications which include wide area coverage, rapid deployment, flexible networking and long range service to moving platforms like ships, aircraft and vehicles. This paper gives an overview of the special features and future trends in military satcom systems. A brief account of various countermeasures against threats, use of EHF, spread-spectrum techniques and on board processing has also been given. Major technological advances are anticipated in near future to realise high capacity, secure and survivable satcom systems for Defence applications.

  4. Global navigation satellite systems, inertial navigation, and integration

    CERN Document Server

    Grewal, Mohinder S; Bartone, Chris G

    2013-01-01

    An updated guide to GNSS, and INS, and solutions to real-world GNSS/INS problems with Kalman filtering Written by recognized authorities in the field, this third edition of a landmark work provides engineers, computer scientists, and others with a working familiarity of the theory and contemporary applications of Global Navigation Satellite Systems (GNSS), Inertial Navigational Systems, and Kalman filters. Throughout, the focus is on solving real-world problems, with an emphasis on the effective use of state-of-the-art integration techniques for those systems, especially the application of Kal

  5. Satellite Constellation Design with Adaptively Continuous Ant System Algorithm

    Institute of Scientific and Technical Information of China (English)

    He Quan; Han Chao

    2007-01-01

    The ant system algorithm (ASA) has proved to be a novel meta-heuristic algorithm to solve many multivariable problems. In this paper, the earth coverage of satellite constellation is analyzed and a (n + 1)-fold coverage rate is put forward to evaluate the coverage performance of a satellite constellation. An optimization model of constellation parameters is established on the basis of the coverage performance. As a newly developed method, ASA can be applied to optimize the constellation parameters. In order to improve the ASA,a rule for adaptive number of ants is proposed, by which the search range is obviously enlarged and the convergence speed increased.Simulation results have shown that the ASA is more quick and efficient than other methods.

  6. Real Time Fire Reconnaissance Satellite Monitoring System Failure Model

    Science.gov (United States)

    Nino Prieto, Omar Ariosto; Colmenares Guillen, Luis Enrique

    2013-09-01

    In this paper the Real Time Fire Reconnaissance Satellite Monitoring System is presented. This architecture is a legacy of the Detection System for Real-Time Physical Variables which is undergoing a patent process in Mexico. The methodologies for this design are the Structured Analysis for Real Time (SA- RT) [8], and the software is carried out by LACATRE (Langage d'aide à la Conception d'Application multitâche Temps Réel) [9,10] Real Time formal language. The system failures model is analyzed and the proposal is based on the formal language for the design of critical systems and Risk Assessment; AltaRica. This formal architecture uses satellites as input sensors and it was adapted from the original model which is a design pattern for physical variation detection in Real Time. The original design, whose task is to monitor events such as natural disasters and health related applications, or actual sickness monitoring and prevention, as the Real Time Diabetes Monitoring System, among others. Some related work has been presented on the Mexican Space Agency (AEM) Creation and Consultation Forums (2010-2011), and throughout the International Mexican Aerospace Science and Technology Society (SOMECYTA) international congress held in San Luis Potosí, México (2012). This Architecture will allow a Real Time Fire Satellite Monitoring, which will reduce the damage and danger caused by fires which consumes the forests and tropical forests of Mexico. This new proposal, permits having a new system that impacts on disaster prevention, by combining national and international technologies and cooperation for the benefit of humankind.

  7. Planning for a data base system to support satellite conceptual design

    Science.gov (United States)

    Claydon, C. R.

    1976-01-01

    The conceptual design of an automated satellite design data base system is presented. The satellite catalog in the system includes data for all earth orbital satellites funded to the hardware stage for launch between 1970 and 1980, and provides a concise compilation of satellite capabilities and design parameters. The cost of satellite subsystems and components will be added to the base. Data elements are listed and discussed. Sensor and science and applications opportunities catalogs will be included in the data system. Capabilities of the BASIS storage, retrieval, and analysis system are used in the system design.

  8. Assessment of a satellite power system and six alternative technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wolsko, T.; Whitfield, R.; Samsa, M.; Habegger, L.S.; Levine, E.; Tanzman, E.

    1981-04-01

    The satellite power system is assessed in comparison to six alternative technologies. The alternatives are: central-station terrestrial photovoltaic systems, conventional coal-fired power plants, coal-gasification/combined-cycle power plants, light water reactor power plants, liquid-metal fast-breeder reactors, and fusion. The comparison is made regarding issues of cost and performance, health and safety, environmental effects, resources, socio-economic factors, and insitutional issues. The criteria for selecting the issues and the alternative technologies are given, and the methodology of the comparison is discussed. Brief descriptions of each of the technologies considered are included. (LEW)

  9. 47 CFR 25.159 - Limits on pending applications and unbuilt satellite systems.

    Science.gov (United States)

    2010-10-01

    ... satellite systems. 25.159 Section 25.159 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Processing of Applications § 25.159 Limits on pending applications and unbuilt satellite systems. (a) Applicants with a total...

  10. Modular High-Energy Systems for Solar Power Satellites

    Science.gov (United States)

    Howell, Joe T.; Carrington, Connie K.; Marzwell, Neville I.; Mankins, John C.

    2006-01-01

    Modular High-Energy Systems are Stepping Stones to provide capabilities for energy-rich infrastructure located in space to support a variety of exploration scenarios as well as provide a supplemental source of energy during peak demands to ground grid systems. Abundant renewable energy at lunar or other locations could support propellant production and storage in refueling scenarios that enable affordable exploration. Renewable energy platforms in geosynchronous Earth orbits can collect and transmit power to satellites, or to Earth-surface locations. Energy-rich space technologies also enable the use of electric-powered propulsion systems that could efficiently deliver cargo and exploration facilities to remote locations. A first step to an energy-rich space infrastructure is a 100-kWe class solar-powered platform in Earth orbit. The platform would utilize advanced technologies in solar power collection and generation, power management and distribution, thermal management, electric propulsion, wireless avionics, autonomous in space rendezvous and docking, servicing, and robotic assembly. It would also provide an energy-rich free-flying platform to demonstrate in space a portfolio of technology flight experiments. This paper summary a preliminary design concept for a 100-kWe solar-powered satellite system to demonstrate in-flight a variety of advanced technologies, each as a separate payload. These technologies include, but are not limited to state-of-the-art solar concentrators, highly efficient multi-junction solar cells, integrated thermal management on the arrays, and innovative deployable structure design and packaging to enable the 100-kW satellite feasible to launch on one existing launch vehicle. Higher voltage arrays and power distribution systems (PDS) reduce or eliminate the need for massive power converters, and could enable direct-drive of high-voltage solar electric thrusters.

  11. Guidance, Navigation, and Control System for Maneuverable Pico-Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A compact, low-power GN&C system is essential to the success of pico-satellite Automated Rendezvous and Docking (AR&D). Austin Satellite Design (ASD)...

  12. Preface: BeiDou Navigation Satellite System (BDS)/GNSS+: Recent progress and new applications

    Science.gov (United States)

    Jin, Shuanggen

    2017-02-01

    Nowadays, the new China's BeiDou Navigation Satellite System (BDS) has been developed well. At the end of 2016, over 23 BDS satellites were launched, including five geostationary Earth orbit (GEO) satellites, five inclined geosynchronous orbit (IGSO) satellites and nine medium Earth orbit (MEO) satellites. The current BDS service covers China and most Asia-Pacific regions with accuracy of better than 10 m in positioning, 0.2 m/s in velocity and 50 ns in timing. The BDS with global coverage will be completely established by 2020 with five GEO satellites and 30 MEO satellites. The main function of BDS is the positioning, navigation and timing (PNT) as well as short message communications. Together with the United States' GPS, Russia's GLONASS and the European Union's Galileo system as well as other regional augmentation systems, more new applications of multi-Global Navigation Satellite Systems (GNSS) will be exploited and realized in the next decades.

  13. Guidance, Navigation, and Control System for Maneuverable Pico-Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Pico-satellites are an emerging new class of spacecraft. Maneuverable pico-satellites require active guidance, navigation, and control (GN&C) systems to perform...

  14. Designing nonuniform satellite systems for continuous global coverage using equatorial and polar circular orbits

    Science.gov (United States)

    Ulybyshev, S. Yu.

    2016-07-01

    We present a method for designing nonuniform satellite systems for continuous global coverage using a combination of equatorial and near-polar satellite segments in circular orbits. Equations are derived to determine the basic design parameters of the satellite system itself and the conditions of its closure at the joint of near-polar and equatorial segments. We analyze specific features of near-polar and equatorial satellite systems and their advantages and disadvantages compared with existing classes of near-polar phased and kinematically correct satellite systems. We estimate the minimum required number of spacecrafts in satellite systems for a given fold of coverage and present calculated dependences for classes of near-polar phased and equatorial satellite systems with different types of closure. For the class of kinematically correct satellite systems, we analyze the characteristics of systems with a minimum spacecraft flight height and reveal that the number of satellites in the orbital plane depends on the flight height for different folds of coverage. We bring examples of the best near-polar equatorial satellite systems of global coverage for different folds and a class of satellite systems with a fixed number of spacecrafts and orbital planes in them.

  15. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Block 3.0 Communications Strategies

    Science.gov (United States)

    Miller, S. W.; Grant, K. D.; Ottinger, K.

    2015-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The JPSS program is the follow-on for both space and ground systems to the Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a globally distributed, multi-mission system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. In a highly successful international partnership between NOAA and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the CGS currently provides data routing from McMurdo Station in Antarctica to the EUMETSAT processing center in Darmstadt, Germany. Continuing and building upon that partnership, NOAA and EUMETSAT are collaborating on the development of a new path forward for the 2020's. One approach being explored is a concept of operations where each organization shares satellite downlink resources with the other. This paper will describe that approach, as well as modeling results that demonstrate its feasibility and expected performance.

  16. Production process for advanced space satellite system cables/interconnects.

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Luis A.

    2007-12-01

    This production process was generated for the satellite system program cables/interconnects group, which in essences had no well defined production process. The driver for the development of a formalized process was based on the set backs, problem areas, challenges, and need improvements faced from within the program at Sandia National Laboratories. In addition, the formal production process was developed from the Master's program of Engineering Management for New Mexico Institute of Mining and Technology in Socorro New Mexico and submitted as a thesis to meet the institute's graduating requirements.

  17. Satellite Power System (SPS) financial/management scenarios

    Science.gov (United States)

    Vajk, J. P.

    1978-01-01

    The possible benefits of a Satellite Power System (SPS) program, both domestically and internationally, justify detailed and imaginative investigation of the issues involved in financing and managing such a large-scale program. In this study, ten possible methods of financing a SPS program are identified ranging from pure government agency to private corporations. The following were analyzed and evaluated: (1) capital requirements for SPS; (2) ownership and control; (3) management principles; (4) organizational forms for SPS; (5) criteria for evaluation; (6) detailed description and preliminary evaluation of alternatives; (7) phased approaches; and (8) comparative evaluation. Key issues and observations and recommendations for further study are also presented.

  18. Handoff algorithm for mobile satellite systems with ancillary terrestrial component

    KAUST Repository

    Sadek, Mirette

    2012-06-01

    This paper presents a locally optimal handoff algorithm for integrated satellite/ground communication systems. We derive the handoff decision function and present the results in the form of tradeoff curves between the number of handoffs and the number of link degradation events in a given distance covered by the mobile user. This is a practical receiver-controlled handoff algorithm that optimizes the handoff process from a user perspective based on the received signal strength rather than from a network perspective. © 2012 IEEE.

  19. Efficient medium access control protocol for geostationary satellite systems

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 顾学迈

    2004-01-01

    This paper proposes an efficient medium access control (MAC) protocol based on multifrequency-time division multiple access (MF-TDMA) for geostationary satellite systems deploying multiple spot-beams and onboard processing,which uses a method of random reservation access with movable boundaries to dynamically request the transmission slots and can transmit different types of traffic. The simulation results have shown that our designed MAC protocol can achieve a high bandwidth utilization, while providing the required quality of service (QoS) for each class of service.

  20. The Federated Satellite Systems paradigm: Concept and business case evaluation

    Science.gov (United States)

    Golkar, Alessandro; Lluch i Cruz, Ignasi

    2015-06-01

    This paper defines the paradigm of Federated Satellite Systems (FSS) as a novel distributed space systems architecture. FSS are networks of spacecraft trading previously inefficiently allocated and unused resources such as downlink bandwidth, storage, processing power, and instrument time. FSS holds the promise to enhance cost-effectiveness, performance and reliability of existing and future space missions, by networking different missions and effectively creating a pool of resources to exchange between participants in the federation. This paper introduces and describes the FSS paradigm, and develops an approach integrating mission analysis and economic assessments to evaluate the feasibility of the business case of FSS. The approach is demonstrated on a case study on opportunities enabled by FSS to enhance space exploration programs, with particular reference to the International Space Station. The application of the proposed methodology shows that the FSS concept is potentially able to create large commercial markets of in-space resources, by providing the technical platform to offer the opportunity for spacecraft to share or make use of unused resources within their orbital neighborhood. It is shown how the concept is beneficial to satellite operators, space agencies, and other stakeholders of the space industry to more flexibly interoperate space systems as a portfolio of assets, allowing unprecedented collaboration among heterogeneous types of missions.

  1. Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

    Directory of Open Access Journals (Sweden)

    Liu Junhong

    2014-10-01

    Full Text Available The visibility for low earth orbit (LEO satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system (GPS. In addition, the spaceborne receivers’ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination (POD results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional (3D accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about 30 cm. As for the precise relative orbit determination (PROD, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit (GEO satellites is illustrated for POD.

  2. Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

    Institute of Scientific and Technical Information of China (English)

    Liu Junhong; Gu Defeng; Ju Bing; Yao Jing; Duan Xiaojun; Yi Dongyun

    2014-01-01

    The visibility for low earth orbit (LEO) satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system (GPS). In addition, the spaceborne receivers’ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satel-lites orbits. The precise orbit determination (POD) results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional (3D) accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about 30 cm. As for the precise relative orbit determination (PROD), the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demon-strates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit (GEO) satellites is illustrated for POD.

  3. Post-launch Radiometric and Spectral Calibration Assessment of NPP/CrIS by Comparing CrIS with VIIRS, AIRS, and IASI

    OpenAIRE

    Wang, Likun; Han, Yong; Tremblay, Denis; Goldberg, Mitch

    2012-01-01

    The Cross-track Infrared Sounder (CrIS) on the newly-launched Suomi National Polar-orbiting Partnership (Suomi NPP) and future Joint Polar Satellite System (JPSS) is a Fourier transform spectrometer that provides soundings of the atmosphere with 1305 spectral channels, over 3 wavelength ranges: LWIR (9.14 - 15.38um); MWIR (5.71 - 8.26um); and SWIR (3.92 - 4.64 um). An accurate spectral and radiometric calibration is fundamental for CrIS radiance Sensor Data Records (SDRs). In this study, thro...

  4. Performance Evaluation of Data Compression Systems Applied to Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Lilian N. Faria

    2012-01-01

    Full Text Available Onboard image compression systems reduce the data storage and downlink bandwidth requirements in space missions. This paper presents an overview and evaluation of some compression algorithms suitable for remote sensing applications. Prediction-based compression systems, such as DPCM and JPEG-LS, and transform-based compression systems, such as CCSDS-IDC and JPEG-XR, were tested over twenty multispectral (5-band images from CCD optical sensor of the CBERS-2B satellite. Performance evaluation of these algorithms was conducted using both quantitative rate-distortion measurements and subjective image quality analysis. The PSNR, MSSIM, and compression ratio results plotted in charts and the SSIM maps are used for comparison of quantitative performance. Broadly speaking, the lossless JPEG-LS outperforms other lossless compression schemes, and, for lossy compression, JPEG-XR can provide lower bit rate and better tradeoff between compression ratio and image quality.

  5. Mobile radio alternative systems study satellite/terrestrial (hybrid) systems concepts

    Science.gov (United States)

    Kiesling, J. D.; Anderson, R. E.

    1983-01-01

    The use of satellites for mobile radio service in non-urban areas of the United States in the years from 1985 to 2000 was investigated. Several satellite concepts are considered: a system with single-beam coverage of the fifty United States and Puerto Rico, and multi-beam satellites with greater capacity. All of the needed functions and services identified in the market study are provided by the satellite systems, including nationwide radio access to vehicles without knowledge of vehicle location wideband data transmission from remote sites, two way exchange of short data and control messages between vehicles and dispatch or control centers, and automatic vehicle location (surveillance). The costs of providing the services are within acceptable limits, and the desired returns to the system investors are attractive. The criteria by which the Federal Communication judges the competing demands for public radio spectrum are reviewed with comments on how the criteria might apply to the consideration of land mobile satellites. Institutional arrangements for operating a mobile satellite system are based on the present institutional arrangements in which the services are offered to the end users through wireline and radio common carriers, with direct access by large private and government users.

  6. A low cost data logging system with satellite transmission capabilities

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.S.; DeSa, E.J.; Desai, R.G.P.

    satellite navigator, deep sea echosounder, and a magnetometer on board a chartered research vessel. A novel data logger design was implemented with the extra option of transmitting logged data through the ships INMARSAT approved satellite terminal...

  7. A system architecture for an advanced Canadian wideband mobile satellite system

    Science.gov (United States)

    Takats, P.; Keelty, M.; Moody, H.

    In this paper, the system architecture for an advanced Canadian ka-band geostationary mobile satellite system is described, utilizing hopping spot beams to support a 256 kbps wideband service for both N-ISDN and packet-switched interconnectivity to small briefcase-size portable and mobile terminals. An assessment is given of the technical feasibility of the satellite payload and terminal design in the post year 2000 timeframe. The satellite payload includes regeneration and on-board switching to permit single hop interconnectivity between mobile terminals. The mobile terminal requires antenna tracking and platform stabilization to ensure acquisition of the satellite signal. The potential user applications targeted for this wideband service includes: home-office, multimedia, desk-top (PC) videoconferencing, digital audio broadcasting, single and multi-user personal communications.

  8. Use of satellite images for the monitoring of water systems

    Science.gov (United States)

    Hillebrand, Gudrun; Winterscheid, Axel; Baschek, Björn; Wolf, Thomas

    2015-04-01

    Satellite images are a proven source of information for monitoring ecological indicators in coastal waters and inland river systems. This potential of remote sensing products was demonstrated by recent research projects (e.g. EU-funded project Freshmon - www.freshmon.eu) and other activities by national institutions. Among indicators for water quality, a particular focus was set on the temporal and spatial dynamics of suspended particulate matter (SPM) and Chlorophyll-a (Chl-a). The German Federal Institute of Hydrology (BfG) was using the Weser and Elbe estuaries as test cases to compare in-situ measurements with results obtained from a temporal series of automatically generated maps of SPM distributions based on remote sensing data. Maps of SPM and Chl-a distributions in European inland rivers and alpine lakes were generated by the Freshmon Project. Earth observation based products are a valuable source for additional data that can well supplement in-situ monitoring. For 2015, the BfG and the Institute for Lake Research of the State Institute for the Environment, Measurements and Nature Conservation of Baden-Wuerttemberg, Germany (LUBW) are in the process to start implementing an operational service for monitoring SPM and Chl-a based on satellite images (Landsat 7 & 8, Sentinel 2, and if required other systems with higher spatial resolution, e.g. Rapid Eye). In this 2-years project, which is part of the European Copernicus Programme, the operational service will be set up for - the inland rivers of Rhine and Elbe - the North Sea estuaries of Elbe, Weser and Ems. Furthermore - Lake Constance and other lakes located within the Federal State of Baden-Wuerttemberg. In future, the service can be implemented for other rivers and lakes as well. Key feature of the project is a data base that holds the stock of geo-referenced maps of SPM and Chl-a distributions. Via web-based portals (e.g. GGInA - geo-portal of the BfG; UIS - environmental information system of the

  9. The changing world of global navigation satellite systems

    Science.gov (United States)

    Dow, John M.; Neilan, Ruth E.; Higgins, Matt; Arias, Felicitas

    The world of global navigation satellite systems (GNSS) has been changing very rapidly during the last years. New constellations are being developed in Europe (Galileo), India (IRNSS), Japan (QZNSS) and China (Compass), while both the US GPS and the Russian GLONASS programmes are engaged in very significant mediumto long-term improvements, which will make them even more valuable in the coming years to an ever wider range of civilian users. In addition, powerful regional augmentation systems are becoming (or have already become) operational, providing users with important real time information concerning the integrity of the signals being broadcast by those two systems: these include the US WAAS, the European EGNOS, the Japanese MSAS, the Indian GAGAN and others. Following a number of United Nations sponsored regional workshops, a report by an ad hoc UN "GNSS Action Team" and several preparatory meetings, the International Committee on GNSS (ICG) was established in December 2005 in Vienna, Austria. The ICG is an informal body with the main objective of promoting cooperation on matters of mutual interest related to civil satellite-based positioning, navigation, timing, and value-added services, as well as compatibility and interoperability among the GNSS systems. A further important objective is to encourage the use of GNSS to support sustainable development, particularly in the developing countries. The United Nations Office for Outer Space Affairs (UNOOSA) plays a key role in facilitating the work of the ICG. The members of the Committee are GNSS system providers, while international organisations representing users of GNSS can qualify for participation in the work of the Committee as associate members or observers. The interests of the space geodetic, mapping and timing communities are represented in particular through ICG associate membership of the IGS, IAG, FIG, IERS, while BIPM is an ICG observer. This paper will highlight the background of these developments

  10. System Design and Key Technologies of the GF-3 Satellite

    Directory of Open Access Journals (Sweden)

    ZHANG Qingjun

    2017-03-01

    Full Text Available GF-3 satellite, the first C band and multi-polarization SAR satellite in China, achieves breakthroughs in a number of core and key technologies. The satellite technology abides by the principle of “Demand Pulls, Technology Pushes”, forming a series of innovation point, and reaching or surpassing international level in main technical specification.

  11. Preliminary environmental assessment for the satellite power system (SPS)

    Energy Technology Data Exchange (ETDEWEB)

    1978-10-01

    A preliminary assessment of the impact of the Satellite Power System (SPS) on the environment is presented. Information that has appeared in documents referenced herein is integrated and assimilated. The state-of-knowledge as perceived from recently completed DOE-sponsored studies is disclosed, and prospective research and study programs that can advance the state-of-knowledge and provide an expanded data base for use in an assessment planned for 1980 are defined. Alternatives for research that may be implemented in order to achieve this advancement are also discussed in order that a plan can be selected which will be consistent with the fiscal and time constraints on the SPS Environmental Assessment Program. Health and ecological effects of microwave radiation, nonmicrowave effects on health and the environment (terrestrial operations and space operations), effects on the atmosphere, and effects on communications systems are examined in detail. (WHK)

  12. A European mobile satellite system concept exploiting CDMA and OBP

    Science.gov (United States)

    Vernucci, A.; Craig, A. D.

    1993-01-01

    This paper describes a novel Land Mobile Satellite System (LMSS) concept applicable to networks allowing access to a large number of gateway stations ('Hubs'), utilizing low-cost Very Small Aperture Terminals (VSAT's). Efficient operation of the Forward-Link (FL) repeater can be achieved by adopting a synchronous Code Division Multiple Access (CDMA) technique, whereby inter-code interference (self-noise) is virtually eliminated by synchronizing orthogonal codes. However, with a transparent FL repeater, the requirements imposed by the highly decentralized ground segment can lead to significant efficiency losses. The adoption of a FL On-Board Processing (OBP) repeater is proposed as a means of largely recovering this efficiency impairment. The paper describes the network architecture, the system design and performance, the OBP functions and impact on implementation. The proposed concept, applicable to a future generation of the European LMSS, was developed in the context of a European Space Agency (ESA) study contract.

  13. The silicon solar satellite power system - A net energy analysis

    Science.gov (United States)

    Hannon, B.; Naughton, J. P.

    The physical aspects and net energy balance of a Satellite Solar Power System (SSPS) are examined. The feasibility of operating with or without laser annealing for the cells, possible variations in the total system costs, the projected worth of the energy, and the R&D costs are explored. The energy needed to mine, refine, fabricate, manufacture, launch, and maintain the SSPS materials and structures are included in the energy analysis, and cost-to-energy ratio of energy used to energy produced graphs are provided for the cases of the use or non-use of laser annealing for radiation protection for the solar cells. The resulting energy ratios indicate that the reference SSPS compares unfavorably with coal or nuclear earth-based plants, although further research is necessary to determine what level of technology is actually required for construction of the SSPS.

  14. NASA ACTS Multibeam Antenna (MBA) System. [Advanced Communications Technology Satellite

    Science.gov (United States)

    Choung, Youn H.; Stiles, W. Herschel; Wu, Joseph; Wong, William C.; Chen, C. Harry

    1986-01-01

    The design of the Advanced Communications Technology Satellite MBA system, which provides both spot beam and scanning beam coverage to both high and low burst rates data-users is examined. The MBA consists of receive and transmit antennas installed on a common precision mounting platform that is integrated to the bus through three flexures; a lightweight system with low thermal distortion is obtained by using composite materials for the MBA structures. The RF design, which is a Cassegrain reflector with a large equivalent focal length/aperture size, is described. Consideration is given to the position of the feed in order to minimize scan loss and sidelobe levels, the size of the subreflector in order to minimize feed spillover, and antenna performance degradation caused by reflector surface distortion. Breadbroad model test result reveal that the maximum sidelobe level outside the 2.5 HPBW region is -30 dB or lower relative to the power.

  15. Satellite-instrument system engineering best practices and lessons

    Science.gov (United States)

    Schueler, Carl F.

    2009-08-01

    This paper focuses on system engineering development issues driving satellite remote sensing instrumentation cost and schedule. A key best practice is early assessment of mission and instrumentation requirements priorities driving performance trades among major instrumentation measurements: Radiometry, spatial field of view and image quality, and spectral performance. Key lessons include attention to technology availability and applicability to prioritized requirements, care in applying heritage, approaching fixed-price and cost-plus contracts with appropriate attention to risk, and assessing design options with attention to customer preference as well as design performance, and development cost and schedule. A key element of success either in contract competition or execution is team experience. Perhaps the most crucial aspect of success, however, is thorough requirements analysis and flowdown to specifications driving design performance with sufficient parameter margin to allow for mistakes or oversights - the province of system engineering from design inception to development, test and delivery.

  16. Onboard Supervisor for the Ørsted Satellite Attitude Control System

    DEFF Research Database (Denmark)

    Bøgh, S.A.; Izadi-Zamanabadi, Roozbeh; Blanke, M.

    1995-01-01

    The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system.......The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system....

  17. UAS CNPC Satellite Link Performance - Sharing Spectrum with Terrestrial Systems

    Science.gov (United States)

    Kerczewski, Robert J.; Wilson, Jeffrey D.; Bishop, William D.

    2016-01-01

    In order to provide for the safe integration of unmanned aircraft systems into the National Airspace System, the control and non-payload communications (CNPC) link connecting the ground-based pilot with the unmanned aircraft must be highly reliable. A specific requirement is that it must operate using aviation safety radiofrequency spectrum. The 2012 World Radiocommunication Conference (WRC-12) provided a potentially suitable allocation for radio line-of-sight (LOS), terrestrial based CNPC link at 5030-5091 MHz. For a beyond radio line-of-sight (BLOS), satellite-based CNPC link, aviation safety spectrum allocations are currently inadequate. Therefore, the 2015 WRC will consider the use of Fixed Satellite Service (FSS) bands to provide BLOS CNPC under Agenda Item 1.5. This agenda item requires studies to be conducted to allow for the consideration of how unmanned aircraft can employ FSS for BLOS CNPC while maintaining existing systems. Since there are terrestrial Fixed Service systems also using the same frequency bands under consideration in Agenda Item 1.5 one of the studies required considered spectrum sharing between earth stations on-board unmanned aircraft and Fixed Service station receivers. Studies carried out by NASA have concluded that such sharing is possible under parameters previously established by the International Telecommunications Union. As the preparation for WRC-15 has progressed, additional study parameters Agenda Item 1.5 have been proposed, and some studies using these parameters have been added. This paper examines the study results for the original parameters as well as results considering some of the more recently proposed parameters to provide insight into the complicated process of resolving WRC-15 Agenda Item 1.5 and achieving a solution for BLOS CNPC for unmanned aircraft.

  18. NNIC—neural network image compressor for satellite positioning system

    Science.gov (United States)

    Danchenko, Pavel; Lifshits, Feodor; Orion, Itzhak; Koren, Sion; Solomon, Alan D.; Mark, Shlomo

    2007-04-01

    We have developed an algorithm, based on novel techniques of data compression and neural networks for the optimal positioning of a satellite. The algorithm is described in detail, and examples of its application are given. The heart of this algorithm is the program NNIC—neural network image compressor. This program was developed for compression color and grayscale images with artificial neural networks (ANNs). NNIC applies three different methods for compression. Two of them are based on neural networks architectures—multilayer perceptron and kohonen network. The third is based on a widely used method of discrete cosine transform, the basis for the JPEG standard. The program also serves as a tool for determining numerical and visual quality parameters of compression and comparison between different methods. A number of advantages and disadvantages of the compression using ANNs were discovered in the course of the present research, some of them presented in this report. The thrust of the report is the discussion of ANNs implementation problems for modern platforms, such as a satellite positioning system that include intensive image flowing and processing.

  19. Evaluation of voice codecs for the Australian mobile satellite system

    Science.gov (United States)

    Bundrock, Tony; Wilkinson, Mal

    1990-01-01

    The evaluation procedure to choose a low bit rate voice coding algorithm is described for the Australian land mobile satellite system. The procedure is designed to assess both the inherent quality of the codec under 'normal' conditions and its robustness under 'severe' conditions. For the assessment, normal conditions were chosen to be random bit error rate with added background acoustic noise and the severe condition is designed to represent burst error conditions when mobile satellite channel suffers from signal fading due to roadside vegetation. The assessment is divided into two phases. First, a reduced set of conditions is used to determine a short list of candidate codecs for more extensive testing in the second phase. The first phase conditions include quality and robustness and codecs are ranked with a 60:40 weighting on the two. Second, the short listed codecs are assessed over a range of input voice levels, BERs, background noise conditions, and burst error distributions. Assessment is by subjective rating on a five level opinion scale and all results are then used to derive a weighted Mean Opinion Score using appropriate weights for each of the test conditions.

  20. Satellite lines at the ionization threshold in charge transfer systems

    Science.gov (United States)

    Wardermann, W.; von Niessen, W.

    1992-01-01

    This article deals with the possibility of low-energy ionizations of reduced intensity for larger organic molecules. Possible mechanisms which may lead to this phenomenon are outlined and the necessary structural features are discussed. The lowest ionization energies of some organic unsaturated nitro and nitroso compounds are calculated by the ADC(3) ab initio many-body Green's function method. The π-electron system consists either of fused five- and six-membered rings or of two fused five-membered rings with a variable number of heteroatoms. Some of the molecules contain exocylic double bonds and some are substituted with the donor groups -NH 2, -OH and -NHOH. The strongest many-body effects are found for the nitroso compounds, where in one case the spectral line at the ionization threshold has lost more than 40% of its intensity to satellites. We study the many-body effects at or close to the ionization threshold for these compounds. A particular mechanism which involves the screening of localized valence holes by charge transfer excitations appears to be capable of influencing the profile and intensities of the ionization spectrum already at the ionization threshold. The effect leads to strongly reduced relative intensities of the bands and may cause the appearance of satellite bands nearly at the ionization threshold. The spectral changes in the outermost valence region are discussed by using a simple model calculation in terms of ground-state electronic properties of the molecules.

  1. Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory

    Institute of Scientific and Technical Information of China (English)

    杨福民; 肖炽昆; 陈婉珍; 张忠萍; 谭德同; 龚向东; 陈菊平; 黄力; 章建华

    1999-01-01

    The first satellite laser ranging system for daylight tracking in China was set up at Shanghai Observatory, Chinese Academy of Sciences. Both false alarm probability due to strong background noises and detection probability of the laser returns with single photon level from satellite in daylight for our system are analysed. The system design and performance characteristics of subsystems, adopted techniques and satellite ranging observations are given.

  2. PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Niederman, Robert A. [Rutgers Univ., New Brunswick, NJ (United States); Blankenship, Robert E. [Washington Univ., St. Louis, MO (United States); Frank, Harry A. [Univ. of Connecticut, Storrs, CT (United States)

    2015-02-07

    These funds were used for partial support of the PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems, that was held on 8-11 August, 2013, at Washington University, St. Louis, MO. This conference, held in conjunction with the 16th International Congress on Photosynthesis/St. Louis, continued a long tradition of light-harvesting satellite conferences that have been held prior to the previous six international photosynthesis congresses. In this Workshop, the basis was explored for the current interest in replacing fossil fuels with energy sources derived form direct solar radiation, coupled with light-driven electron transport in natural photosynthetic systems and how they offer a valuable blueprint for conversion of sunlight to useful energy forms. This was accomplished through sessions on the initial light-harvesting events in the biological conversion of solar energy to chemically stored energy forms, and how these natural photosynthetic processes serve as a guide to the development of robust bio-hybrid and artificial systems for solar energy conversion into both electricity or chemical fuels. Organized similar to a Gordon Research Conference, a lively, informal and collegial setting was established, highlighting the exchange of exciting new data and unpublished results from ongoing studies. A significant amount of time was set aside for open discussion and interactive poster sessions, with a special session devoted to oral presentations by talented students and postdoctoral fellows judged to have the best posters. This area of research has seen exceptionally rapid progress in recent years, with the availability of a number of antenna protein structures at atomic resolution, elucidation of the molecular surface architecture of native photosynthetic membranes by atomic force microscopy and the maturing of ultrafast spectroscopic and molecular biological techniques for the investigation and manipulation of photosynthetic systems. The conferees

  3. Satellite power system. Concept development and evaluation program

    Energy Technology Data Exchange (ETDEWEB)

    1978-10-01

    The Reference System description emphasizes technical and operational information required in support of environmental, socioeconomic, and comparative assessment studies. Supporting information has been developed according to a guideline of implementing two 5 GW SPS systems per year for 30 years beginning with an initial operational data of 2000 and with SPS's being added at the rate of two per year (10 GW/year) until 2030. The Reference System concept, which features gallium--aluminum--arsenide (GaAlAs) and silicon solar cell options, is described in detail. The concept utilizes a planar solar array (about 55 km/sup 2/) built on a graphite fiber reinforced thermoplastic structure. The silicon array uses a concentration ratio of one (no concentration), whereas the GaAlAs array uses a concentration ratio of two. A one-kilometer diameter phased array microwave antenna is mounted on one end. The antenna uses klystrons as power amplifiers with slotted waveguides as radiating elements. The satellite is constructed in geosynchronous orbit in a six-month period. The ground receiving stations (rectenna) are completed during the same time period. The other two major components of an SPS program are (1) the construction bases in space and launch and mission control bases on earth and (2) fleets of various transportation vehicles that support the construction and maintenance operations of the satellites. These transportation vehicles include Heavy Lift Launch Vehicles (HLLV), Personnel Launch Vehicles (PLV), Cargo Orbit Transfer Vehicles (COTV), and Personnel Orbit Transfer Vehicles (POTV). The earth launch site chosen is the Kennedy Space Center, pending further study.

  4. Satellite Data Assimilation within KIAPS-LETKF system

    Science.gov (United States)

    Jo, Y.; Lee, S., Sr.; Cho, K.

    2016-12-01

    Korea Institute of Atmospheric Prediction Systems (KIAPS) has been developing an ensemble data assimilation system using four-dimensional local ensemble transform kalman filter (LETKF; Hunt et al., 2007) within KIAPS Integrated Model (KIM), referred to as "KIAPS-LETKF". KIAPS-LETKF system was successfully evaluated with various Observing System Simulation Experiments (OSSEs) with NCAR Community Atmospheric Model - Spectral Element (Kang et al., 2013), which has fully unstructured quadrilateral meshes based on the cubed-sphere grid as the same grid system of KIM. Recently, assimilation of real observations has been conducted within the KIAPS-LETKF system with four-dimensional covariance functions over the 6-hr assimilation window. Then, conventional (e.g., sonde, aircraft, and surface) and satellite (e.g., AMSU-A, IASI, GPS-RO, and AMV) observations have been provided by the KIAPS Package for Observation Processing (KPOP). Wind speed prediction was found most beneficial due to ingestion of AMV and for the temperature prediction the improvement in assimilation is mostly due to ingestion of AMSU-A and IASI. However, some degradation in the simulation of the GPS-RO is presented in the upper stratosphere, even though GPS-RO leads positive impacts on the analysis and forecasts. We plan to test the bias correction method and several vertical localization strategies for radiance observations to improve analysis and forecast impacts.

  5. Global Navigation Satellite Systems (GNSS: The Utmost Interdisciplinary Integrator

    Directory of Open Access Journals (Sweden)

    Bernd Eissfeller

    2015-08-01

    Full Text Available Currently four global satellite navigation systems are under modernization and development: The US American GPS III, the Russian GLONASS, the European Galileo and Chinese BeiDou systems. In the paper the interdisciplinary contributions of different scientific areas to GNSS are assessed. It is outlined that GNSS is not only a technical system but also a basic element of mobile computing high-tech market. At the same time a GNSS has the role of a force enabler in security related applications. Technology, market and security policies are interdependent and are sometimes in a relationship of tension. The goal of the paper is to describe the overall systemics of GNSS from a holistic point of view. The paper also addresses the human factor side of GNSS. The requirements on human resources in GNSS are at least two-fold: On the one hand very specialized engineers are needed; on the other hand the generalists are necessary who are able to understand the system aspects. Decision makers in institutions and industry need special knowledge in technologies, economics and political strategies. Is the current university system able to educate and prepare such generalists? Are specialized master courses for GNSS needed? Are external training courses necessary?

  6. Global tracking and inventory of military hardware via LEO satellite: A system approach and likely scenario

    Science.gov (United States)

    Bell, David; Estabrook, Polly; Romer, Richard

    1995-01-01

    A system for global inventory control of electronically tagged military hardware is achievable using a LEO satellite constellation. An equipment Tag can communicate directly to the satellite with a power of 5 watts or less at a data rate of 2400 to 50,000 bps. As examples, two proposed commercial LEO systems, IRIDIUM and ORBCOMM, are both capable of providing global coverage but with dramatically different telecom capacities. Investigation of these two LEO systems as applied to the Tag scenario provides insight into satellite design trade-offs, constellation trade-offs and signal dynamics that effect the performance of a satellite-based global inventory control system.

  7. Medium-rate speech coding simulator for mobile satellite systems

    Science.gov (United States)

    Copperi, Maurizio; Perosino, F.; Rusina, F.; Albertengo, G.; Biglieri, E.

    1986-01-01

    Channel modeling and error protection schemes for speech coding are described. A residual excited linear predictive (RELP) coder for bit rates 4.8, 7.2, and 9.6 kbit/sec is outlined. The coder at 9.6 kbit/sec incorporates a number of channel error protection techniques, such as bit interleaving, error correction codes, and parameter repetition. Results of formal subjective experiments (DRT and DAM tests) under various channel conditions, reveal that the proposed coder outperforms conventional LPC-10 vocoders by 2 subjective categories, thus confirming the suitability of the RELP coder at 9.6 kbit/sec for good quality speech transmission in mobile satellite systems.

  8. Tracking wildlife by satellite: Current systems and performance

    Science.gov (United States)

    Harris, Richard B.; Fancy, Steven G.; Douglas, David C.; Garner, Gerald W.; Amstrup, Steven C.; McCabe, Thomas R.; Pank, Larry F.

    1990-01-01

    Since 1984, the U.S. Fish and Wildlife Service has used the Argos Data Collection and Location System (DCLS) and Tiros-N series satellites to monitor movements and activities of 10 species of large mammals in Alaska and the Rocky Mountain region. Reliability of the entire system was generally high. Data were received from instrumented caribou (Rangifer tarandus) during 91% of 318 possible transmitter-months. Transmitters failed prematurely on 5 of 45 caribou, 2 of 6 muskoxen (Ovibos moschatus), and 1 of 2 gray wolves (Canis lupus). Failure rates were considerably higher for polar (Ursus maritimus) and brown (U. arctos) bears than for caribou (Rangifer tarandus). Efficiency of gathering both locational and sensor data was related to both latitude and topography.Mean error of locations was estimated to be 954 m (median = 543 m) for transmitters on captive animals; 90% of locations were <1,732 m from the true location. Argos's new location class zero processing provided many more locations than normal processing, but mean location error was much higher than locations estimated normally. Locations were biased when animals were at elevations other than those used in Argos's calculations.Long-term and short-term indices of animal activity were developed and evaluated. For several species, the long-term index was correlated with movement patterns and the short-term index was calibrated to specific activity categories (e.g., lying, feeding, walking).Data processing and sampling considerations were evaluated. Algorithms for choosing the most reliable among a series of reported locations were investigated. Applications of satellite telemetry data and problems with lack of independence among locations are discussed.

  9. Preliminary Analysis of a Novel SAR Based Emergency System for Earth Orbit Satellites using Galileo

    NARCIS (Netherlands)

    Gill, E.K.A.; Helderweirt, A.

    2010-01-01

    This paper presents a preliminary analysis of a novel Search and Rescue (SAR) based emergency system for Low Earth Orbit (LEO) satellites using the Galileo Global Navigation Satellite System (GNSS). It starts with a description of the space user SAR system including a concept description, mission ar

  10. A general interactive system for compositing digital radar and satellite data

    Science.gov (United States)

    Ghosh, K. K.; Chen, L. C.; Faghmous, M.; Heymsfield, G. M.

    1981-01-01

    Reynolds and Smith (1979) have considered the combined use of digital weather radar and satellite data in interactive systems for case study analysis and forecasting. Satellites view the top of clouds, whereas radar is capable of observing the detailed internal structure of clouds. The considered approach requires the use of a common coordinate system. In the present investigation, it was decided to use the satellite coordinate system as the base system in order to maintain the fullest resolution of the satellite data. The investigation is concerned with the development of a general interactive software system called RADPAK for remapping and analyzing conventional and Doppler radar data. RADPAK is implemented as a part of a minicomputer-based image processing system, called Atmospheric and Oceanographic Image Processing System. Attention is given to a general description of the RADPAK system, remapping methodology, and an example of satellite remapping.

  11. The National Polar-orbiting Operational Environmental Satellite System

    Science.gov (United States)

    Bloom, H.

    The tri-agency Integrated Program Office (IPO) is responsible for managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current military and civilian operational polar-orbiting ``weather'' satellites. The Northrop Grumman Space Technology - Raytheon team was competitively selected in 2002 as the Acquisition and Operations contractor team to develop, integrate, deploy, and operate NPOESS satellites to meet the tri-agency user requirements for NPOESS over the 10-year (2009-2018) operational life of the program. Beginning in 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving operational ``weather'' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - atmosphere, ocean, land, and the space environment. In recent years, the operational weather forecasting and climate science communities have levied more rigorous requirements on space-based observations of the Earth's system that have significantly increased demands on performance of the instruments, spacecraft, and ground systems required to deliver NPOESS data, products, and information to end users. The ``end-to-end'' system consists of: the spacecraft; instruments and sensors on the spacecraft; launch support capabilities; the command, control, communications, and data routing infrastructure; and data processing hardware and software. NPOESS will observe significantly more phenomena simultaneously from space than its operational predecessors. NPOESS is expected to deliver large volumes of more accurate measurements at higher spatial (horizontal and vertical) and temporal resolution at much higher data

  12. Gas data transmission system by satellite telephone; Systeme de transmission de donnees sur le gaz utilisant le telephone par satellite

    Energy Technology Data Exchange (ETDEWEB)

    Ogasawara, S.; Tanji, A. [Dengineer Co., Ltd (Japan); Akiyama, S. [Buyo Gas Company (Japan)

    2000-07-01

    Dengineer Co., Ltd. and Buyo Gas Co., Ltd. had been developing and using the data and alarm transmission system by public telephone since 1984, that was first practical use in Japan. It is very important for business management that adjusts the production value of gas by measuring gas pressures in each governor. Also, it is indispensable to know the accident of gas leakage or abnormal gas pressure quickly. But this convenient system is not spread yet in Japanese market cause of the following reasons. - Take time and cost for installation of terminal station. - Terminal station is apt to damage by thunder. - Big disaster must stop working this system. In order to solve those problems, we have developed and tested the system organized of the satellite telephone system and solar cells for power. This system will be very useful for wide place, not only Japanese market but also the area, which has no electricity and phone. Also, it will be convenient for international rescue as is able to access it from the foreign countries. (authors)

  13. FQPSK techniques for satellite and mobile radio communications systems

    Science.gov (United States)

    Li, Yazhuo; Tang, Jing; Tao, Xiaofeng

    2005-11-01

    A continuous phase modulation (CPM) and constant envelope modulation (CEM) alternative of Feher-Patented quadrature phase-shift keying (FQPSK) modulation technique is presented. It is found to provide good spectral efficiencies, power efficiencies, and bit error rate (BER) performance. The modulation schemes of FQPSK are described. The spectral efficiencies, BER performance are also compared with FQPSK and other modulation techniques which are widely used in current mobile and cordless radio standards. The results show that FQPSK modulated signal exhibits much less spectrum spreading than QPSK, OQPSK, and MSK, and the error probability performance of the FQPSK is superior to those in narrow-band nonlinear channels. Based on that, the system capacity and power dissipation are also analyzed for communication systems. It is found that the encoder or receiver for the FQPSK signal to be fully compatible with original I/Q modulated one. FQPSK technique is suitable for nonlinear channels, such as satellite and mobile communications systems reducing the AM/AM and AM/PM adverse effects. At last it is also attempted to extend the application in 3G (CDMA) and 4G (OFDM) mobile communications systems.

  14. A Ku-band satellite system for the cable television industry

    Science.gov (United States)

    Napoli, Joseph

    This paper describes the satellite requirements for the Ku-band used for satellite delivery of television programming. The case for using the Ku-band is reviewed, including the business benefits to the cable industry, the superior protection against failure, the pace of technical advances, and the channel capacity. The characteristics of the satellites carrying the Ku-band are described, and a protection plan for the satellites is considered. The technical characteristics of the Ku-band and related systems considerations are addressed. Signal outage at the Ku-band is discussed, and Ku-band receiving system design is examined, including system installation and operations.

  15. A MEO Tracking and Data Relay Satellite System Constellation Scheme for China

    Institute of Scientific and Technical Information of China (English)

    WU Ting-yong; WU Shi-qi; LING Xiang

    2005-01-01

    A medium earth orbit (MEO) tracking and data relay satellite system (TDRSS) constellation scheme for China is proposed. This system consists of MEO satellite constellation, inter-satellite links (ISLs) and terrestrial gateway station, which can provide continuous bidirectional data transmission links between low altitude spacecrafts and the terrestrial gateway station in China. Theoretical analysis and simulation results indicate that the proposed constellation can cover the global low altitude space sphere and earth surface of China continuously, and has a preferable practical perspective.

  16. Magnetometer Compensation Scheme and Experimental Results on ZDPS-1A Pico-satellite

    Institute of Scientific and Technical Information of China (English)

    HAN Ke; WANG Hao; XIANG Tian; JIN Zhonghe

    2012-01-01

    In a pico-satellite with small volume,measurements from on-board three-axis magnetometer (TAM) are not accurate,as it can be easily disturbed by other electronic systems.To improve its accuracy,a scheme of compensation mcthods is introduced in this article.The scheme is based on an improved measurement model of pico-satellite TAM,and it mainly consists of three steps.First,in satellite design stage,several techniques are recommended to simplify the afterwards compensations.Then after satellite assembly,TAM ground tests and pre-launch calibration with least-square batch filter are introduced to improve magnetometer performance.At the end,a post-launch calibration with unscented Kalman filter (UKF) is implemented with in-orbit data.The compensation scheme is used in the development of Chinese pico-satellite ZDPS-1A made by Zhejiang University.Results show that with the introduced compensation scheme,the maximum error of ZDPS-1A TAM can be reduced from 80 mG to 6 mG (1G=10-4 T).

  17. Adaptive beamforming in a CDMA mobile satellite communications system

    Science.gov (United States)

    Munoz-Garcia, Samuel G.

    1993-01-01

    Code-Division Multiple-Access (CDMA) stands out as a strong contender for the choice of multiple access scheme in these future mobile communication systems. This is due to a variety of reasons such as the excellent performance in multipath environments, high scope for frequency reuse and graceful degradation near saturation. However, the capacity of CDMA is limited by the self-interference between the transmissions of the different users in the network. Moreover, the disparity between the received power levels gives rise to the near-far problem, this is, weak signals are severely degraded by the transmissions from other users. In this paper, the use of time-reference adaptive digital beamforming on board the satellite is proposed as a means to overcome the problems associated with CDMA. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference sources. Since CDMA is interference limited, the interference protection provided by the antenna converts directly and linearly into an increase in capacity. Furthermore, the proposed concept allows the near-far effect to be mitigated without requiring a tight coordination of the users in terms of power control. A payload architecture will be presented that illustrates the practical implementation of this concept. This digital payload architecture shows that with the advent of high performance CMOS digital processing, the on-board implementation of complex DSP techniques -in particular digital beamforming- has become possible, being most attractive for Mobile Satellite Communications.

  18. Laser Communication Demonstration System (LCDS) and future mobile satellite services

    Science.gov (United States)

    Chen, Chien-Chung; Wilhelm, Michael D.; Lesh, James R.

    1995-01-01

    The Laser Communications Demonstration System (LCDS) is a proposed in-orbit demonstration of high data rate laser communications technology conceived jointly by NASA and U.S. industry. The program objectives are to stimulate industry development and to demonstrate the readiness of high data rate optical communications in Earth orbit. For future global satellite communication systems using intersatellite links, laser communications technology can offer reduced mass and power requirements and higher channel bandwidths without regulatory constraints. As currently envisioned, LCDS will consist of one or two orbiting laser communications terminals capable of demonstrating high data rate (greater than 750Mbps) transmission in a dynamic space environment. Two study teams led by Motorola and Ball Aerospace are currently in the process of conducting a Phase A/B mission definition study of LCDS under contracts with JPL/NASA. The studies consist of future application survey, concept and requirements definition, and a point design of the laser communications flight demonstration. It is planned that a single demonstration system will be developed based on the study results. The Phase A/B study is expected to be completed by the coming June, and the current results of the study are presented in this paper.

  19. Deep Charging Evaluation of Satellite Power and Communication System Components

    Science.gov (United States)

    Schneider, T. A.; Vaughn, J. A.; Chu, B.; Wong, F.; Gardiner, G.; Wright, K. H.; Phillips, B.

    2016-01-01

    Deep charging, in contrast to surface charging, focuses on electron penetration deep into insulating materials applied over conductors. A classic example of this scenario is an insulated wire. Deep charging can pose a threat to material integrity, and to sensitive electronics, when it gives rise to an electrostatic discharge or arc. With the advent of Electric Orbit Raising, which requires spiraling through Earth's radiation belts, satellites are subjected to high energy electron environments which they normally would not encounter. Beyond Earth orbit, missions to Jupiter and Saturn face deep charging concerns due to the high energy radiation environments. While predictions can be made about charging in insulating materials, it is difficult to extend those predictions to complicated geometries, such as the case of an insulating coating around a small wire, or a non-uniform silicone grouting on a bus bar. Therefore, to conclusively determine the susceptibility of a system to arcs from deep charging, experimental investigations must be carried out. This paper will describe the evaluation carried out by NASA's Marshall Space Flight Center on subscale flight-like samples developed by Space Systems/Loral, LLC. Specifically, deep charging evaluations of solar array wire coupons, a photovoltaic cell coupon, and a coaxial microwave transmission cable, will be discussed. The results of each evaluation will be benchmarked against control sample tests, as well as typical power system levels, to show no significant deep charging threat existed for this set of samples under the conditions tested.

  20. Advanced payload concepts and system architecture for emerging services in Indian National Satellite Systems

    Science.gov (United States)

    Balasubramanian, E. P.; Rao, N. Prahlad; Sarkar, S.; Singh, D. K.

    2008-07-01

    Over the past two decades Indian Space Research Organization (ISRO) has developed and operationalized satellites to generate a large capacity of transponders for telecommunication service use in INSAT system. More powerful on-board transmitters are built to usher-in direct-to-home broadcast services. These have transformed the Satcom application scenario in the country. With the proliferation of satellite technology, a shift in the Indian market is witnessed today in terms of demand for new services like Broadband Internet, Interactive Multimedia, etc. While it is imperative to pay attention to market trends, ISRO is also committed towards taking the benefits of technological advancement to all round growth of our population, 70% of which dwell in rural areas. The initiatives already taken in space application related to telemedicine, tele-education and Village Resource Centres are required to be taken to a greater height of efficiency. These targets pose technological challenges to build a large capacity and cost-effective satellite system. This paper addresses advanced payload concepts and system architecture along with the trade-off analysis on design parameters in proposing a new generation satellite system capable of extending the reach of the Indian broadband structure to individual users, educational and medical institutions and enterprises for interactive services. This will be a strategic step in the evolution of INSAT system to employ advanced technology to touch every human face of our population.

  1. FORMATION OF MULTIPLE-SATELLITE SYSTEMS FROM LOW-MASS CIRCUMPLANETARY PARTICLE DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Hyodo, Ryuki; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Takeda, Takaaki, E-mail: ryukih@stu.kobe-u.ac.jp, E-mail: ohtsuki@tiger.kobe-u.ac.jp [VASA Entertainment Co. Ltd. (Japan)

    2015-01-20

    Circumplanetary particle disks would be created in the late stage of planetary formation either by impacts of planetary bodies or disruption of satellites or passing bodies, and satellites can be formed by accretion of disk particles spreading across the Roche limit. Previous N-body simulation of lunar accretion focused on the formation of single-satellite systems from disks with large disk-to-planet mass ratios, while recent models of the formation of multiple-satellite systems from disks with smaller mass ratios do not take account of gravitational interaction between formed satellites. In the present work, we investigate satellite accretion from particle disks with various masses, using N-body simulation. In the case of accretion from somewhat less massive disks than the case of lunar accretion, formed satellites are not massive enough to clear out the disk, but can become massive enough to gravitationally shepherd the disk outer edge and start outward migration due to gravitational interaction with the disk. When the radial location of the 2:1 mean motion resonance of the satellite reaches outside the Roche limit, the second satellite can be formed near the disk outer edge, and then the two satellites continue outward migration while being locked in the resonance. Co-orbital satellites are found to be occasionally formed on the orbit of the first satellite. Our simulations also show that stochastic nature involved in gravitational interaction and collision between aggregates in the tidal environment can lead to diversity in the final mass and orbital architecture, which would be expected in satellite systems of exoplanets.

  2. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Current Technical Performance Measures

    Science.gov (United States)

    Cochran, S.; Panas, M.; Jamilkowski, M. L.; Miller, S. W.

    2015-12-01

    ABSTRACT The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture is being upgraded to Block 2.0 in 2015 to "operationalize" S-NPP, leverage lessons learned to date in multi-mission support, take advantage of more reliable and efficient technologies, and satisfy new requirements and constraints in the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 49 Technical Performance Measures (TPMs) across 10 categories, such as data latency, operational availability and scalability. This paper will provide an overview of the CGS Block 2.0 architecture, with particular focus on the 10 TPM categories listed above. We will provide updates on how we ensure the deployed architecture meets these TPMs to satisfy our multi-mission objectives with the deployment of Block 2.0.

  3. Satellite Power System (SPS) FY 79 Program Summary

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    The Satellite Power System (SPS) program is a joint effort of the US Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA). It is managed by the SPS Project Office within DOE's Office of Energy Research. SPS project organization is shown in Figure 1. The SPS Project Office was established in 1978 and is responsible for the planning, management and integration of SPS research in four areas: systems definition, environmental assessment, societal assessment, and comparative assessment. In fulfilling its responsibilities, the SPS Project Office directs research and assessment efforts to determine the feasibility of the SPS concept, funds organizations supporting the program, and disseminates information developed from project research and assessments. The objective of the SPS program is to develop an initial understanding of the technical feasibility, the economic practicality, and the social and environmental acceptability of the SPS concept. This is being accomplished through implementation of the Concept Development and Evaluation Program Plan which is scheduled for completion by the end of FY 1980. The SPS Project Office annually issues a Program Summary which describes the research undertaken during the preceding fiscal year. This Program Summary covers FY 1979. It includes work completed in FY 1977 and FY 1978 in order to give a comprehensive picture of the DOE involvement in the SPS concept development and evaluation process.

  4. A Positioning System based on Communication Satellites and the Chinese Area Positioning System (CAPS)

    Science.gov (United States)

    Ai, Guo-Xiang; Shi, Hu-Li; Wu, Hai-Tao; Yan, Yi-Hua; Bian, Yu-Jing; Hu, Yong-Hui; Li, Zhi-Gang; Guo, Ji; Xian-DeCai

    2008-12-01

    The Chinese Area Positioning System (CAPS) is a positioning system based on satellite communication that is fundamentally different from the 3``G'' (GPS, GLONASS and GALILEO) systems. The latter use special-purpose navigation satellites to broadcast navigation information generated on-board to users, while the CAPS transfers ground-generated navigation information to users via the communication satellite. In order to achieve accurate Positioning, Velocity and Time (PVT), the CAPS employs the following strategies to overcome the three main obstacles caused by using the communication satellite: (a) by real-time following-up frequency stabilization to achieve stable frequency; (b) by using a single carrier in the transponder with 36 MHz band-width to gain sufficient power; (c) by incorporating Decommissioned Geostationary Orbit communication satellite (DGEO), barometric pressure and Inclined Geostationary Orbit communication satellite (IGSO) to achieve the 3-D positioning. Furthermore, the abundant transponders available on DGEO can be used to realize the large capacity of communication as well as the integrated navigation and communication. With the communication functions incorporated, five new functions appear in the CAPS: (1) combination of navigation and communication; (2) combination of navigation and high accuracy orbit measurement; (3) combination of navigation message and wide/local area differential processing; (4) combination of the switching of satellites, frequencies and codes; and (5) combination of the navigation message and the barometric altimetry. The CAPS is thereby labelled a PVT5C system of high accuracy. In order to validate the working principle and the performance of the CAPS, a trial system was established in the course of two years at a cost of about 20 million dollars. The trial constellation consists of two GEO satellites located at E87.5° and E110.5°, two DGEOs located at E130° and E142°, as well as barometric altimetry as a virtual

  5. A Positioning System based on Communication Satellites and the Chinese Area Positioning System (CAPS)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Chinese Area Positioning System (CAPS) is a positioning system based on satellite communication that is fundamentally different from the 3"G" (GPS, GLONASS and GALILEO) systems. The latter use special-purpose navigation satellites to broadcast navi-gation information generated on-board to users, while the CAPS transfers ground-generated navigation information to users via the communication satellite. In order to achieve accurate Positioning, Velocity and Time (PVT), the CAPS employs the following strategies to over-come the three main obstacles caused by using the communication satellite: (a) by real-time following-up frequency stabilization to achieve stable frequency; (b) by using a single carrier in the transponder with 36 MHz band-width to gain sufficient power; (c) by incorporating Decommissioned Geostationary Orbit communication satellite (DGEO), barometric pressure and Inclined Geostationary Orbit communication satellite (IGSO) to achieve the 3-D posi-tioning. Furthermore, the abundant transponders available on DGEO can be used to realize the large capacity of communication as well as the integrated navigation and communication. With the communication functions incorporated, five new functions appear in the CAPS: (1) combination of navigation and communication; (2) combination of navigation and high accu-racy orbit measurement; (3) combination of navigation message and wide/local area differen-tial processing; (4) combination of the switching of satellites, frequencies and codes; and (5) combination of the navigation message and the barometric altimetry. The CAPS is thereby labelled a PVT5C system of high accuracy. In order to validate the working principle and the performance of the CAPS, a trial system was established in the course of two years at a cost of about 20 million dollars. The trial constellation consists of two GEO satellites located at E87.5°and E110.5°, two DGEOs located at E130° and E142°, as well as barometric altimetry as a virtual

  6. A classification system for virophages and satellite viruses.

    Science.gov (United States)

    Krupovic, Mart; Kuhn, Jens H; Fischer, Matthias G

    2016-01-01

    Satellite viruses encode structural proteins required for the formation of infectious particles but depend on helper viruses for completing their replication cycles. Because of this unique property, satellite viruses that infect plants, arthropods, or mammals, as well as the more recently discovered satellite-like viruses that infect protists (virophages), have been grouped with other, so-called "sub-viral agents." For the most part, satellite viruses are therefore not classified. We argue that possession of a coat-protein-encoding gene and the ability to form virions are the defining features of a bona fide virus. Accordingly, all satellite viruses and virophages should be consistently classified within appropriate taxa. We propose to create four new genera - Albetovirus, Aumaivirus, Papanivirus, and Virtovirus - for positive-sense single-stranded (+) RNA satellite viruses that infect plants and the family Sarthroviridae, including the genus Macronovirus, for (+)RNA satellite viruses that infect arthopods. For double-stranded DNA virophages, we propose to establish the family Lavidaviridae, including two genera, Sputnikvirus and Mavirus.

  7. System Design and In-orbit Verification of the HJ-1-C SAR Satellite

    OpenAIRE

    Zhang Run-ning; Jiang Xiu-peng

    2014-01-01

    HJ-1-C is a SAR satellite owned by the Chinese Environment and Natural Disaster Monitoring constellation, and works together with the optical satellites HJ-1-A/B for monitoring environment and natural disasters. In this paper, the system design and characteristics of the first Chinese civil SAR satellite are described. In addition, the interface relation between SAR payload and platform is studied. Meanwhile, the data transmission capability, attitude, power, and temperature control that supp...

  8. A discussion on mobile satellite system and the myths of CDMA and diversity revealed

    Science.gov (United States)

    Hart, Nicholas; Goerke, Thomas; Jahn, Axel

    1995-01-01

    The paper explores the myths and facts surrounding: link margins and constellation designs; the use of satellite diversity in a mobile satellite channel; trade-offs in multiple access technique. Different satellite constellations are presented, which are comparable with those used by the big LEO proponents, with the associated trade-offs in the system design. Propagation data and results from various narrowband and wideband measurement campaigns are used to illustrate the expected differences in service performance.

  9. Ground Simulation of an Autonomous Satellite Rendezvous and Tracking System Using Dual Robotic Systems

    Science.gov (United States)

    Trube, Matthew J.; Hyslop, Andrew M.; Carignan, Craig R.; Easley, Joseph W.

    2012-01-01

    A hardware-in-the-loop ground system was developed for simulating a robotic servicer spacecraft tracking a target satellite at short range. A relative navigation sensor package "Argon" is mounted on the end-effector of a Fanuc 430 manipulator, which functions as the base platform of the robotic spacecraft servicer. Machine vision algorithms estimate the pose of the target spacecraft, mounted on a Rotopod R-2000 platform, relay the solution to a simulation of the servicer spacecraft running in "Freespace", which performs guidance, navigation and control functions, integrates dynamics, and issues motion commands to a Fanuc platform controller so that it tracks the simulated servicer spacecraft. Results will be reviewed for several satellite motion scenarios at different ranges. Key words: robotics, satellite, servicing, guidance, navigation, tracking, control, docking.

  10. Excitation of inclinations in ring-satellite systems

    Science.gov (United States)

    Borderies, N.; Goldreich, P.; Tremaine, S.

    1984-01-01

    Resonant gravitational interactions between a ring and a satellite produce secular variations of their orbital inclinations. Interactions at vertical resonances, analogous to Lindblad resonances but involving inclinations instead of eccentricities, excite inclinations. There is no inclination analog of the corotation resonance. An equatorial ring changes the inclination of a nearby satellite in qualitatively the same way that a satellite in an equatorial orbit changes the inclination of a nearby ring. Viscous dissipation in a ring leads to an equilibrium value of its inclination. These results provide a basis for discussing the origins of the inclinations of planetary rings.

  11. Multichannel demultiplexer/demodulator technologies for future satellite communication systems

    Science.gov (United States)

    Ivancic, William D.; Budinger, James M.; Staples, Edward J.; Abramovitz, Irwin; Courtois, Hector A.

    1992-01-01

    NASA-Lewis' Space Electronics Div. supports ongoing research in advanced satellite communication architectures, onboard processing, and technology development. Recent studies indicate that meshed VSAT (very small aperture terminal) satellite communication networks using FDMA (frequency division multiple access) uplinks and TDMA (time division multiplexed) downlinks are required to meet future communication needs. One of the critical advancements in such a satellite communication network is the multichannel demultiplexer/demodulator (MCDD). The progress is described which was made in MCDD development using either acousto-optical, optical, or digital technologies.

  12. G-MAP: a novel night vision system for satellites

    Science.gov (United States)

    Miletti, Thomas; Maresi, Luca; Zuccaro Marchi, Alessandro; Pontetti, Giorgia

    2015-10-01

    The recent developments of single-photon counting array detectors opens the door to a novel type of systems that could be used on satellites in low Earth orbit. One possible application is the detection of non-cooperative vessels or illegal fishing activities. Currently only surveillance operations conducted by Navy or coast guard address this topic, operations by nature costly and with limited coverage. This paper aims to describe the architectural design of a system based on a novel single-photon counting detector, which works mainly in the visible and features fast readout, low noise and a 256x256 matrix of 64 μm-pixels. This detector is positioned in the focal plane of a fully aspheric reflective f/6 telescope, to guarantee state of the art performance. The combination of the two grants optimal ground sampling distance, compatible with the average dimension of a vessel, and overall performance. A radiative analysis of the light transmitted from emission to detection is presented, starting from models of lamps used for attracting fishes and illuminating the deck of the boats. A radiative transfer model is used to estimate the amount of photons emitted by such vessels reaching the detector. Since the novel detector features high framerate and low noise, the system as it is envisaged is able to properly serve the proposed goal. The paper shows the results of a trade-off between instrument parameters and spacecraft operations to maximize the detection probability and the covered sea surface. The status of development of both detector and telescope are also described.

  13. Classification of Satellite Resonances in the Solar System

    Science.gov (United States)

    Luan, Jing; Goldreich, Peter

    2017-01-01

    Several pairs of solar system satellites occupy mean motion resonances (MMRs). We divide these into two groups according to their proximity to exact resonance. Proximity is measured by the existence of a separatrix in phase space. MMRs between Io–Europa, Europa–Ganymede, and Enceladus–Dione are too distant from exact resonance for a separatrix to appear. A separatrix is present only in the phase spaces of the Mimas–Tethys and Titan–Hyperion MMRs, and their resonant arguments are the only ones to exhibit substantial librations. Could there be a causal connection between the libration amplitude and the presence of a separatrix? Our suspicions were aroused by Goldreich & Schlichting, who demonstrate that sufficiently deep in a MMR, eccentricity damping could destabilize librations. However, our investigation reveals that libration amplitudes in both the Mimas–Tethys and Titan–Hyperion MMRs are fossils. Although the Mimas–Tethys MMR is overstable, its libration amplitude grows on the tidal damping timescale of Mimas’s inclination, which is considerably longer than a Hubble time. On the other hand, the Titan–Hyperion MMR is stable, but tidal damping of Hyperion’s eccentricity is too weak to have affected the amplitude of its libration.

  14. Fates of satellite ejecta in the Saturn system, II

    Science.gov (United States)

    Alvarellos, José Luis; Dobrovolskis, Anthony R.; Zahnle, Kevin J.; Hamill, Patrick; Dones, Luke; Robbins, Stuart

    2017-03-01

    We assess the fates of ejecta from the large craters Aeneas on Dione and Ali Baba on Enceladus (161 and 39 km in diameter, respectively), as well as that from Herschel (130 km in diameter) on Mimas. The ejecta are treated either as 'spalls' launched from hard surfaces, or as 'rubble' launched from a weak rubble pile regolith. Once in orbit we consider the ejecta as massless test particles subject to the gravity of Saturn and its classical satellites. The great majority of escaped ejecta get swept up by the source moons. The best fit to the ejecta population decay is a stretched exponential with exponent near 1/2 (Dobrovolskis et al., Icarus 188, 481-505, 2007). We bracket the characteristic ejecta sizes corresponding to Grady-Kipp fragments and spalls. Based on this and computed impact velocities and incidence angles, the resulting sesquinary craters, if they exist, should have diameters on the order of a few meters to a few km. The observed longitude distribution of small craters on Mimas along with the findings of Bierhaus et al. that small moons should not have a secondary crater population (Icarus 218, 602-621, 2012) suggest that the most likely place to find sesquinary craters in the Saturn system is the antapex of Mimas.

  15. Multifunctional astronomical self-organizing system of autonomous navigation and orientation for artificial Earth satellites

    Science.gov (United States)

    Kuznetsov, V. I.; Danilova, T. V.

    2017-03-01

    We describe the methods and algorithms of a multifunctional astronomical system of the autonomous navigation and orientation for artificial Earth satellites based on the automatization of the system approach to the design and programming problems of the subject area.

  16. The Cyclone Global Navigation Satellite System (CYGNSS) - Analysis and Data Assimilation for Tropical Convection

    Science.gov (United States)

    Li, Xuanli; Lang, Timothy J.; Mecikalski, John; Castillo, Tyler; Hoover, Kacie; Chronis, Themis

    2017-01-01

    Cyclone Global Navigation Satellite System (CYGNSS): a constellation of 8 micro-satellite observatories launched in November 2016, to measure near-surface oceanic wind speed. Main goal: To monitor surface wind fields of the Tropical Cyclones' inner core, including regions beneath the intense eye wall and rain bands that could not previously be measured from space; Cover 38 deg S -38 deg N with unprecedented temporal resolution and spatial coverage, under all precipitating conditions Low flying satellite: Pass over ocean surface more frequently than one large satellite. A median(mean) revisit time of 2.8(7.2) hrs.

  17. Design and implementation of an experiment scheduling system for the ACTS satellite

    Science.gov (United States)

    Ringer, Mark J.

    1994-01-01

    The Advanced Communication Technology Satellite (ACTS) was launched on the 12th of September 1993 aboard STS-51. All events since that time have proceeded as planned with user operations commencing on December 6th, 1993. ACTS is a geosynchronous satellite designed to extend the state of the art in communication satellite design and is available to experimenters on a 'time/bandwidth available' basis. The ACTS satellite requires the advance scheduling of experimental activities based upon a complex set of resource, state, and activity constraints in order to ensure smooth operations. This paper describes the software system developed to schedule experiments for ACTS.

  18. Defining and representing events in a satellite scheduling system - The IEPS (Interactive Experimenter Planning System) approach

    Science.gov (United States)

    McLean, David R.; Littlefield, Ronald G.; Macoughtry, William O.

    A methodology is described for defining and representing satellite events from the IEPS perspective. The task of doing this is divided into four categories and includes defining and representing resource windows, event parameters, event scheduling strategies, and event constraints. The description of each of these categories includes examples from the IEPS ERBS-TDRSS Contact Planning System. This is a system which is being used by the Earth Radiation Budget Satellite (ERBS) schedulers to request TDRSS contact times from the NCC. The system is written in the C programming language and uses a custom built inference engine (TIE1) to do constraint checking and a custom built strategies interpreter to derive the plan. The planning system runs on the IBM-PC/AT or on any similar hardware which has a C development environment and 640K of memory.

  19. System architecture and market aspects of an European Land Mobile Satellite System via EMS

    Science.gov (United States)

    Ananasso, F.; Mistretta, I.

    1992-03-01

    The paper describes an implementation scenario of a Land Mobile Satellite System via the EMS (European Mobile System) payload embarked on Italsat F-2. Some emphasis is given on market issues aiming at singling out business niches of Land Mobile Satellite Services (LMSS) in Europe. Other crucial issues exist such as: the alternate/competitive systems, the problems of interworking with other existing and/or planned systems, the definition of network architecture that better fits the user requirements, the marketing strategy and, last but not least, the financial evaluation of the project. The paper, on the basis of a study performed by Telespazio on behalf of ESA, discusses some of these issues with emphasis on competitive market aspects.

  20. The integrated satellite-acoustic telemetry (iSAT) system for tracking marine megafauna

    KAUST Repository

    De La Torre, Pedro R.

    2012-10-06

    This document describes the integrated satellite-acoustic telemetry (iSAT) system: an autonomous modular system for tracking the movements of large pelagic fish using acoustic telemetry and satellite communications. The sensor platform is described along with the propulsion and navigation systems. An application for tracking the whale shark (Rhincodon typus) in the Red Sea is included along with a discussion of the technical difficulties that such a system faces.

  1. A satellite system for multimedia personal communications at Ka-band and beyond

    Science.gov (United States)

    Vatalaro, F.; Losquadro, G.

    1995-01-01

    The main characteristics of the satellite extremely high frequency (EHF) communication of multimedia mobile services (SECOMS) system are given and the results of the preliminary analysis are included. The SECOMS provides a first generation Ka band system with coverage over Western Europe, in order to satisfy business user needs of very large bandwidths and terminal mobility. The satellite system also provides a second generation EHF enhanced system with increased capacity and enlarged coverage, to serve all of Europe and the nearby countries.

  2. A comparing design of satellite attitude control system based on reaction wheel

    Institute of Scientific and Technical Information of China (English)

    CHENG Hao; GE Sheng-min; SHEN Yi

    2008-01-01

    The disturbance caused by the reaction wheel with a current controller greatly influences the accuracy and stability of the satellite attitude control system.To solve this problem,the idea of speed feedback compensation control reaction wheel is put forward.This paper introduces the comparison on design and performance of two satellite attitude control systems,which are separately based on the current control reaction wheel and the speed feedback compensation control reaction wheel.Analysis shows that the speed feedback compensation control flywheel system may effectively suppress the torque fluctuation.Simulation results indicate that the satellite attitude control system with the speed feedback compensation control flywheel has improved performance.

  3. Integration between terrestrial-based and satellite-based land mobile communications systems

    Science.gov (United States)

    Arcidiancono, Antonio

    A survey is given of several approaches to improving the performance and marketability of mobile satellite systems (MSS). The provision of voice/data services in the future regional European Land Mobile Satellite System (LMSS), network integration between the Digital Cellular Mobile System (GSM) and LMSS, the identification of critical areas for the implementation of integrated GSM/LMSS areas, space segment scenarios, LMSS for digital trunked private mobile radio (PMR) services, and code division multiple access (CDMA) techniques for a terrestrial/satellite system are covered.

  4. Integration between terrestrial-based and satellite-based land mobile communications systems

    Science.gov (United States)

    Arcidiancono, Antonio

    1990-01-01

    A survey is given of several approaches to improving the performance and marketability of mobile satellite systems (MSS). The provision of voice/data services in the future regional European Land Mobile Satellite System (LMSS), network integration between the Digital Cellular Mobile System (GSM) and LMSS, the identification of critical areas for the implementation of integrated GSM/LMSS areas, space segment scenarios, LMSS for digital trunked private mobile radio (PMR) services, and code division multiple access (CDMA) techniques for a terrestrial/satellite system are covered.

  5. Europa Jupiter System Mission (EJSM): Exploration Of The Jovian System And Its Icy Satellites

    Science.gov (United States)

    Grasset, Olivier; Pappalardo, R.; Greeley, R.; Blanc, M.; Dougherty, M.; Bunce, E.; Lebreton, J.; Prockter, L.; Senske, D.; EJSM Joint Science Definition Team

    2009-09-01

    The Europa Jupiter System Mission (EJSM) would be an international mission with the overall theme of investigating the emergence of habitable worlds around gas giants. Its goals are to (1) Determine whether the Jupiter system harbors habitable worlds and (2) Characterize the processes that are operating within the Jupiter system. NASA and ESA have concluded a detailed joint study of a mission to Europa, Ganymede, and the Jupiter system with orbiters developed by NASA and ESA (future contributions by JAXA and Russia are also possible). The baseline EJSM architecture consists of two primary elements operating in the Jovian system: the NASA-led Jupiter Europa Orbiter (JEO), and the ESA-led Jupiter Ganymede Orbiter (JGO). JEO and JGO would execute an intricately choreographed exploration of the Jupiter System before settling into orbit around Europa and Ganymede, respectively. EJSM would directly address themes concerning the origin and evolution of satellite systems and water-rich environments in icy satellites. The potential habitability of the ocean-bearing moons Europa and Ganymede would be investigated, by characterizing the geophysical, compositional, geological, and external processes that affect these icy worlds. EJSM would also investigate Io and Callisto, Jupiter's atmosphere, and the Jovian magnetosphere. By understanding the Jupiter system and unraveling its history, the formation and evolution of gas giant planets and their satellites would be better known. Most important, EJSM would shed new light on the potential for the emergence of life in the celestial neighborhood and beyond. The EJSM architecture provides opportunities for coordinated synergistic observations by JEO and JGO of the Jupiter and Ganymede magnetospheres, the volcanoes and torus of Io, the atmosphere of Jupiter, and comparative planetology of icy satellites. Each spacecraft would conduct both synergistic dual-spacecraft investigations and "stand-alone” measurements.

  6. Microfluidic separation of satellite droplets as the basis of a monodispersed micron and submicron emulsification system.

    Science.gov (United States)

    Tan, Yung-Chieh; Lee, Abraham Phillip

    2005-10-01

    Emulsions are widely used to produce sol-gel, drugs, synthetic materials, and food products. Recent advancements in microfluidic droplet emulsion technology has enabled the precise sampling and processing of small volumes of fluids (picoliter to femtoliter) by the controlled viscous shearing in microchannels. However the generation of monodispersed droplets smaller than 1 microm without surfactants has been difficult to achieve. Normally, the generation of satellite droplets along with parent droplets is undesirable and makes it difficult to control volume and purity of samples in droplets. In this paper, however, several methods are presented to passively filter out satellite droplets from the generation of parent droplets and use these satellite droplets as the source for monodispersed production of submicron emulsions. A passive satellite droplet filtration system and a dynamic satellite droplet separation system are demonstrated. Satellite droplets are filtered from parent droplets with a two-layer channel geometry. This design allows the creation and collection of droplets that are less than 100 nm in diameter. In the dynamic separation system, satellite droplets of defined sizes can be selectively separated into different collecting zones. The separation of the satellite droplets into different collecting zones correlates with the cross channel position of the satellite droplets during the breakup of the liquid thread. The delay time for droplets to switch between the different alternating collecting zones is nominally 1 min and is proportional to the ratio of the oil shear flows. With our droplet generation system, monodispersed satellite droplets with an average radius of 2.23 +/- 0.11 microm, and bidispersed secondary and tertiary satellite droplets with radii of 1.55 +/- 0.07 microm and 372 +/- 46 nm respectively, have been dynamically separated and collected.

  7. Design and simulation of satellite attitude control system based on Simulink and VR

    Science.gov (United States)

    Zhang, Yang; Gan, Qingbo; Kang, Jingshu

    2016-01-01

    In order to research satellite attitude control system design and visual simulation, the simulation framework of satellite dynamics and attitude control using Simulink were established. The design of satellite earth-oriented control system based on quaternion feedback was completed. The 3D scene based on VR was created and models in the scene were driven by simulation data of Simulink. By coordinate transformation. successful observing the scene in inertial coordinate system, orbit coordinate system and body coordinate system. The result shows that application of simulation method of Simulink combined with VR in the design of satellite attitude control system field, has the advantages of high confidence level, hard real-time property, multi-perspective and multi-coordinate system observing the scene, and improves the comprehensibility and accuracy of the design.

  8. Dutch Micro Systems Technology for the Next Generation of Small Satellites

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    Advanced microelectronics and Micro Systems Technology (MST) enable an increased functional performance of small satellites with decreased demands on mass, size and power. The research and development cluster MISAT stimulates the design and development of advanced small satellite platforms based on

  9. Dutch Micro Systems Technology for the Next Generation of Small Satellites

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    Advanced microelectronics and Micro Systems Technology (MST) enable an increased functional performance of small satellites with decreased demands on mass, size and power. The research and development cluster MISAT stimulates the design and development of advanced small satellite platforms based on

  10. Satellite Power Systems (SPS) concept definition study. Volume 2, part 2: System engineering

    Science.gov (United States)

    Hanley, G. M.

    1980-09-01

    The latest technical and programmatic developments are considered as well as expansions of the Rockwell SPS cost model covering each phase of the program through the year 2030. Comparative cost/economic analyses cover elements of the satellite, construction system, space transportation vehicles and operations, and the ground receiving station. System plans to define time phased costs and planning requirements that support major milestones through the year 2000. A special analysis is included on natural resources required to build the SPS reference configuration. An appendix contains the SPS Work Breakdown Structure and dictionary along with detail cost data sheet on each system and main element of the program. Over 200 line items address DDT&E, theoretical first unit, investment cost per satellite, and operations charges for replacement capital and normal operations and maintenance costs.

  11. Satellite Power Systems (SPS) concept definition study. Volume 2, part 2: System engineering. [cost and programmatics

    Science.gov (United States)

    Hanley, G. M.

    1980-01-01

    The latest technical and programmatic developments are considered as well as expansions of the Rockwell SPS cost model covering each phase of the program through the year 2030. Comparative cost/economic analyses cover elements of the satellite, construction system, space transportation vehicles and operations, and the ground receiving station. System plans to define time phased costs and planning requirements that support major milestones through the year 2000. A special analysis is included on natural resources required to build the SPS reference configuration. An appendix contains the SPS Work Breakdown Structure and dictionary along with detail cost data sheet on each system and main element of the program. Over 200 line items address DDT&E, theoretical first unit, investment cost per satellite, and operations charges for replacement capital and normal operations and maintenance costs.

  12. Monte Carlo simulations of precise timekeeping in the Milstar communication satellite system

    Science.gov (United States)

    Camparo, James C.; Frueholz, R. P.

    1995-01-01

    The Milstar communications satellite system will provide secure antijam communication capabilities for DOD operations into the next century. In order to accomplish this task, the Milstar system will employ precise timekeeping on its satellites and at its ground control stations. The constellation will consist of four satellites in geosynchronous orbit, each carrying a set of four rubidium (Rb) atomic clocks. Several times a day, during normal operation, the Mission Control Element (MCE) will collect timing information from the constellation, and after several days use this information to update the time and frequency of the satellite clocks. The MCE will maintain precise time with a cesium (Cs) atomic clock, synchronized to UTC(USNO) via a GPS receiver. We have developed a Monte Carlo simulation of Milstar's space segment timekeeping. The simulation includes the effects of: uplink/downlink time transfer noise; satellite crosslink time transfer noise; satellite diurnal temperature variations; satellite and ground station atomic clock noise; and also quantization limits regarding satellite time and frequency corrections. The Monte Carlo simulation capability has proven to be an invaluable tool in assessing the performance characteristics of various timekeeping algorithms proposed for Milstar, and also in highlighting the timekeeping capabilities of the system. Here, we provide a brief overview of the basic Milstar timekeeping architecture as it is presently envisioned. We then describe the Monte Carlo simulation of space segment timekeeping, and provide examples of the simulation's efficacy in resolving timekeeping issues.

  13. 77 FR 51045 - Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Notice of...

    Science.gov (United States)

    2012-08-23

    ... COMMISSION Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Notice of... Commission has received a complaint entitled Certain Two-Way Global Satellite Communication Devices, System... satellite communication devices, systems. The complaint names as respondents Delorme Publishing Company Inc...

  14. Preliminary environmental assessment for the satellite power system (SPS). Revision 1. Volume 1. Executive summary

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    A preliminary assessment of the environmental impacts of the proposed satellite power system (SPS) is summarized here. In this system, satellites would collect solar energy in space, convert it to microwaves, and transmit the microwaves to receiving antennas (rectennas) on earth. At the rectennas, the microwaves would be converted to electricity. The assessment considers microwave and nonmicrowave effects on the terrestrial environment and human health, atmospheric effects, and disruption of communications and other electromagnetic systems.

  15. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System.

    Science.gov (United States)

    Jan, Shau-Shiun; Tao, An-Lin

    2016-05-13

    The Chinese BeiDou navigation satellite system (BDS) aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS) is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA) methods, three signal quality analysis (SQA) methods, and four measurement quality analysis (MQA) methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region.

  16. ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites

    Science.gov (United States)

    Logalbo, P.; Benedicto, J.; Viola, R.

    1993-01-01

    Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

  17. ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites

    Science.gov (United States)

    Logalbo, P.; Benedicto, J.; Viola, R.

    Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

  18. A novel approach for simulating the optical misalignment caused by satellite platform vibration in the ground test of satellite optical communication systems.

    Science.gov (United States)

    Wang, Qiang; Tan, Liying; Ma, Jing; Yu, Siyuan; Jiang, Yijun

    2012-01-16

    Satellite platform vibration causes the misalignment between incident direction of the beacon and optical axis of the satellite optical communication system, which also leads to the instability of the laser link and reduces the precision of the system. So how to simulate the satellite platform vibration is a very important work in the ground test of satellite optical communication systems. In general, a vibration device is used for simulating the satellite platform vibration, but the simulation effect is not ideal because of the limited randomness. An approach is reasonable, which uses a natural random process for simulating the satellite platform vibration. In this paper, we discuss feasibility of the concept that the effect of angle of arrival fluctuation is taken as an effective simulation of satellite platform vibration in the ground test of the satellite optical communication system. Spectrum characteristic of satellite platform vibration is introduced, referring to the model used by the European Space Agency (ESA) in the SILEX program and that given by National Aeronautics and Space Development Agency (NASDA) of Japan. Spectrum characteristic of angle of arrival fluctuation is analyzed based on the measured data from an 11.16km bi-directional free space laser transmission experiment. Spectrum characteristic of these two effects is compared. The results show that spectra of these two effects have similar variation trend with the variation of frequency and feasibility of the concept is proved by the comparison results. At last the procedure of this method is proposed, which uses the power spectra of angle of arrival fluctuation to simulate that of the satellite platform vibration. The new approach is good for the ground test of satellite optical communication systems.

  19. Introducing multisensor satellite radiance-based evaluation for regional Earth System modeling

    Science.gov (United States)

    Matsui, T.; Santanello, J.; Shi, J. J.; Tao, W.-K.; Wu, D.; Peters-Lidard, C.; Kemp, E.; Chin, M.; Starr, D.; Sekiguchi, M.; Aires, F.

    2014-07-01

    Earth System modeling has become more complex, and its evaluation using satellite data has also become more difficult due to model and data diversity. Therefore, the fundamental methodology of using satellite direct measurements with instrumental simulators should be addressed especially for modeling community members lacking a solid background of radiative transfer and scattering theory. This manuscript introduces principles of multisatellite, multisensor radiance-based evaluation methods for a fully coupled regional Earth System model: NASA-Unified Weather Research and Forecasting (NU-WRF) model. We use a NU-WRF case study simulation over West Africa as an example of evaluating aerosol-cloud-precipitation-land processes with various satellite observations. NU-WRF-simulated geophysical parameters are converted to the satellite-observable raw radiance and backscatter under nearly consistent physics assumptions via the multisensor satellite simulator, the Goddard Satellite Data Simulator Unit. We present varied examples of simple yet robust methods that characterize forecast errors and model physics biases through the spatial and statistical interpretation of various satellite raw signals: infrared brightness temperature (Tb) for surface skin temperature and cloud top temperature, microwave Tb for precipitation ice and surface flooding, and radar and lidar backscatter for aerosol-cloud profiling simultaneously. Because raw satellite signals integrate many sources of geophysical information, we demonstrate user-defined thresholds and a simple statistical process to facilitate evaluations, including the infrared-microwave-based cloud types and lidar/radar-based profile classifications.

  20. Introducing Multisensor Satellite Radiance-Based Evaluation for Regional Earth System Modeling

    Science.gov (United States)

    Matsui, T.; Santanello, J.; Shi, J. J.; Tao, W.-K.; Wu, D.; Peters-Lidard, C.; Kemp, E.; Chin, M.; Starr, D.; Sekiguchi, M.; hide

    2014-01-01

    Earth System modeling has become more complex, and its evaluation using satellite data has also become more difficult due to model and data diversity. Therefore, the fundamental methodology of using satellite direct measurements with instrumental simulators should be addressed especially for modeling community members lacking a solid background of radiative transfer and scattering theory. This manuscript introduces principles of multisatellite, multisensor radiance-based evaluation methods for a fully coupled regional Earth System model: NASA-Unified Weather Research and Forecasting (NU-WRF) model. We use a NU-WRF case study simulation over West Africa as an example of evaluating aerosol-cloud-precipitation-land processes with various satellite observations. NU-WRF-simulated geophysical parameters are converted to the satellite-observable raw radiance and backscatter under nearly consistent physics assumptions via the multisensor satellite simulator, the Goddard Satellite Data Simulator Unit. We present varied examples of simple yet robust methods that characterize forecast errors and model physics biases through the spatial and statistical interpretation of various satellite raw signals: infrared brightness temperature (Tb) for surface skin temperature and cloud top temperature, microwave Tb for precipitation ice and surface flooding, and radar and lidar backscatter for aerosol-cloud profiling simultaneously. Because raw satellite signals integrate many sources of geophysical information, we demonstrate user-defined thresholds and a simple statistical process to facilitate evaluations, including the infrared-microwave-based cloud types and lidar/radar-based profile classifications.

  1. Real-Time Orbit Determination for Future Korean Regional Navigation Satellite System

    Science.gov (United States)

    Shin, Kihae; Oh, Hyungjik; Park, Sang-Young; Park, Chandeok

    2016-03-01

    This paper presents an algorithm for Real-Time Orbit Determination (RTOD) of navigation satellites for the Korean Regional Navigation Satellite System (KRNSS), when the navigation satellites generate ephemeris by themselves in abnormal situations. The KRNSS is an independent Regional Navigation Satellite System (RNSS) that is currently within the basic/preliminary research phase, which is intended to provide a satellite navigation service for South Korea and neighboring countries. Its candidate constellation comprises three geostationary and four elliptical inclined geosynchronous orbit satellites. Relative distance ranging between the KRNSS satellites based on Inter-Satellite Ranging (ISR) is adopted as the observation model. The extended Kalman filter is used for real-time estimation, which includes fine-tuning the covariance, measurement noise, and process noise matrices. Simulation results show that ISR precision of 0.3-0.7 m, ranging capability of 65,000 km, and observation intervals of less than 20 min are required to accomplish RTOD accuracy to within 1 m. Furthermore, close correlation is confirmed between the dilution of precision and RTOD accuracy.

  2. Key issues of multiple access technique for LEO satellite communication systems

    Institute of Scientific and Technical Information of China (English)

    温萍萍; 顾学迈

    2004-01-01

    The large carrier frequency shift caused by the high-speed movement of satellite (Doppler effects) and the propagation delay on the up-down link are very critical issues in an LEO satellite communication system, which affects both the selection and the implementation of a suitable access method. A Doppler based multiple access technique is used here to control the flow and an MPRMA-HS protocol is proposed for the application in LEO satellite communication systems. The extended simulation trials prove that the proposed scheme seems to be a very promising access method.

  3. Numerical exploration of resonant dynamics in the system of Saturnian major satellites

    Science.gov (United States)

    Callegari, N.; Yokoyama, T.

    2010-12-01

    We numerically investigate the long-term dynamics of the Saturnian system by analyzing the Fourier spectra of ensembles of orbits taken around the current orbits of Mimas, Enceladus, Tethys, Rhea and Hyperion. We construct dynamical maps around the current position of these satellites in their respective phase spaces. The maps are the result of a great deal of numerical simulations where we adopt dense sets of initial conditions and different satellite configurations. Several structures associated to the current two-body mean-motion resonances, unstable regions associated to close approaches between the satellites, and three-body mean-motion resonances in the system, are identified in the map.

  4. Technical and programmatic constraints in dynamic verification of satellite mechanical systems

    Science.gov (United States)

    Stavrinidis, C.; Klein, M.; Brunner, O.; Newerla, A.

    1996-01-01

    The development and verification of satellite systems covers various programmatic options. In the mechanical systems area, spacecraft test verification options include static, shaker vibration, modal survey, thermoelastic, acoustic, impact and other environmental tests. Development and verification tests influence the provision of satellite hardware, e.g. the structural model, engineering model, flight model, postflight etc., which need to be adopted by projects. In particular, adequate understanding of the satellite dynamic characteristics is essential for flight acceptance by launcher authorities. In general, a satellite shaker vibration test is requested by launcher authorities for expendable launchers. For the latter the launcher/satellite interface is well defined at the launcher clampband/separation device, and the interface is considered conveniently as a single point at the centre of the clampband. Recently the need has been identified to refine the interface idealization in launcher/satellite coupled loads dynamic analysis, particularly in cases where concentrated satellite loads are introduced at the interface, e.g. platform support struts. In the case of shuttle payloads, which are attached directly to the shuttle, shaker vibration at a single interface is not meaningful. Shuttle launcher authorities require identification of the satellite dynamic characteristics, e.g. by modal survey, and structural verification can be demonstrated by analysis, testing or a combination of analysis and testing. In the case of large satellite systems, which cannot be tested due to the limitation of the vibration shaker test facilities, a similar approach can be adapted for expendable launchers. In such an approach the dynamic characteristics of the satellite system will be identified by the modal survey test, and detailed satellite verification/qualification will be accomplished by analysis supported by subsystem and component level tests. Mechanical strength verification

  5. Global maritime mobile service via satellite - The INMARSAT system now and in the future

    Science.gov (United States)

    Snowball, A. E.

    1986-06-01

    The business and technical aspects of the INMARSAT (International Maritime Satellite Organization) system are reviewed along with its present capabilities and services and future developments now being considered. The initial phase of maritime mobile satellite communications began with the introduction by the U.S. of the Marisat system in 1976, satisfying a commitment made by COMSAT (Communications Satellite Corp.) in 1973 to provide a maritime satellite service. The Marisat Consortium, spun off by COMSAT, launched three satellites in 1973 - one to serve shipping in the Atlantic, one for the Pacific, and the third as a spare; the spare was subsequently positioned over the Indian Ocean so that the three provided almost global coverage. Each satellite was served by a coast earth station with a 13-m antenna; satellite-earth station links operated in the 6 and 4-GHz bands and the ship-satellite links were at 1.5 and 1.6 GHz. Superceding the limited Marisat system, the INMARSAT Organization, established in July 1979 and first in service on Feb. 1, 1982, now provides communications through a system of Marecs, Intelsat-V, and Marisat satellites. With 41 Signatories by mid-1985, the organization consists of an Assembly, a Council, and a Directorate. Services provided include: telephone; facsimile; low-speed data; high-speed data; telex; telegram; distress, urgency and safety communications; shore-to-ship group calls; various information and assistance services. Coast earth stations, ship earth stations, network coordination stations, and the London headquarters and operations control center are described. Future developments will include an expanded capacity network, digital services, and a role in the Future Global Maritime Distress and Safety System that will use radio beacons that will automatically transmit distress messages to land-based emergency centers in the event of a disaster at sea.

  6. An Image-Based Sensor System for Autonomous Rendez-Vous with Uncooperative Satellites

    CERN Document Server

    Miravet, Carlos; Krouch, Eloise; del Cura, Juan Manuel

    2008-01-01

    In this paper are described the image processing algorithms developed by SENER, Ingenieria y Sistemas to cope with the problem of image-based, autonomous rendez-vous (RV) with an orbiting satellite. The methods developed have a direct application in the OLEV (Orbital Life Extension Extension Vehicle) mission. OLEV is a commercial mission under development by a consortium formed by Swedish Space Corporation, Kayser-Threde and SENER, aimed to extend the operational life of geostationary telecommunication satellites by supplying them control, navigation and guidance services. OLEV is planned to use a set of cameras to determine the angular position and distance to the client satellite during the complete phases of rendez-vous and docking, thus enabling the operation with satellites not equipped with any specific navigational aid to provide support during the approach. The ability to operate with un-equipped client satellites significantly expands the range of applicability of the system under development, compar...

  7. The state of the atmosphere as inferred from the FGGE satellite observing systems during SOP-1

    Science.gov (United States)

    Halem, M.; Kalnay, E.; Baker, W. E.; Atlas, R.

    1981-01-01

    Data assimilation experiments were performed to test the influence of different elements of the satellite observing systems. Results from some of the experiments are presented. These findings show that the FGGE satellite systems are able to infer the three-dimensional motion field and improve the representation of the large-scale state of the atmosphere. Preliminary results of the forecast impact of the FGGE data sets are also presented.

  8. Propagation Models for Dimensioning and Estimation of Performance and Availability of New Satellite Communication Systems

    OpenAIRE

    2001-01-01

    A rapid growth of new satellite systems utilizing the Ka-band (27 – 40 Ghz) and even higher frequencies is expected in the coming years. The services offered will include broadband communication, interactive broadcasting, multimedia applications, interconnection of local area networks and Internet connectivity. Many of the new systems will use technologies as multiple spot-beams, onboard processing, and switching of packets between beams and inter satellite links. Because of congestion in the...

  9. Propagation effects handbook for satellite systems design. A summary of propagation impairments on 10 to 100 GHz satellite links with techniques for system design

    Science.gov (United States)

    Ippolito, Louis J.

    1989-01-01

    The NASA Propagation Effects Handbook for Satellite Systems Design provides a systematic compilation of the major propagation effects experienced on space-Earth paths in the 10 to 100 GHz frequency band region. It provides both a detailed description of the propagation phenomenon and a summary of the impact of the effect on the communications system design and performance. Chapter 2 through 5 describe the propagation effects, prediction models, and available experimental data bases. In Chapter 6, design techniques and prediction methods available for evaluating propagation effects on space-Earth communication systems are presented. Chapter 7 addresses the system design process and how the effects of propagation on system design and performance should be considered and how that can be mitigated. Examples of operational and planned Ku, Ka, and EHF satellite communications systems are given.

  10. A Synthetic Aperture System Based on Backscattering Signals of Compass Navigation Satellite: Concept and Feasibility

    Directory of Open Access Journals (Sweden)

    Wang Hai-yang

    2012-06-01

    Full Text Available A concept of a bi-static geosynchronous synthetic aperture system, which is formed by reusing backscattered signals of Compass Navigation Satellite System (CNSS, is proposed. The geometric relations of a geostationary satellite of CNSS, located on a geosynchronous satellite receiver, which is illuminated by the backscattered energy of a satellite of CNSS, and a ground station is built up, and following the relations as well as principle of synthetic aperture radar, we expatiate the feasibility of the system by considering parameters such as imaging resolution, ratio of signal to noise and link budget, etc.. Besides, the potential remote sensing applications for measurement of terrain humidity, characteristics of space-time dynamics of changing of terrain surface and atmospheric characteristic, etc..

  11. Design description report for a photovoltaic power system for a remote satellite earth terminal

    Science.gov (United States)

    Marshall, N. A.; Naff, G. J.

    1987-01-01

    A photovoltaic (PV) power system has been installed as an adjunct to an agricultural school at Wawatobi on the large northern island of the Republic of Indonesia. Its purpose is to provide power for a satellite earth station and a classroom. The renewable energy developed supports the video and audio teleconferencing systems as well as the facility at large. The ground station may later be used to provide telephone service. The installation was made in support of the Agency for International Development's Rural Satellite Program, whose purpose is to demonstrate the use of satellite communications for rural development assistance applications. The objective of this particular PV power system is to demonstrate the suitability of a hybrid PV engine-generator configuration for remote satellite earth stations.

  12. Communication Systems through Artificial Earth Satellites (Selected Pages)

    Science.gov (United States)

    1987-02-05

    POX Fs (8.2.11) is 0(F) dF If on input of weighing circuit fluctuation noise with uniform spectrum acts, spectral power density in numerator and...Possibly also realization MV with asynchronous operation of terrestrial stations, that we will designate through MVA . In the case MVA each terrestrial...according to the frequcrncy. With MVA through receiving-transmitting equipment of satellite into some tiMe intervals simultaneous possible passage of signals

  13. Study of LEO-SAT microwave link for broad-band mobile satellite communication system

    Science.gov (United States)

    Fujise, Masayuki; Chujo, Wataru; Chiba, Isamu; Furuhama, Yoji; Kawabata, Kazuaki; Konishi, Yoshihiko

    1993-01-01

    In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented.

  14. New Generation of Broadcasting Satellite Systems: New Markets and Business Developments

    Science.gov (United States)

    Perrot, Bruno; Michel, Cyril; Villaret, Stéfanie

    2002-01-01

    Since the deployment of the first Digital Broadcasting Satellite Systems, European satellite operators and service providers have been faced with the continuously increasing demand for Digital Broadcasting Services. Their success is built on the availability of the MPEG and DVB standards. Undoubtedly, conventional digital television broadcasting is today the `Killer' application. Various service providers already offer multimedia applications through DVB-S systems based upon the `Push' technology. Although these services do not currently represent the core business for broadcasting satellite operators, their percentage is increasing. `Push' technology services include Data Carousel, Webcasting, Turbo Internet, File casting and so on. Such technology can support the implementation of different emerging multimedia services scenarios from Newsgroups, Network collaborative learning, and tele-medicine, to others that may be invented in the near future. The penetration rate of multi-channel television reception is still increasing. Broadcasting satellites benefit both from the development of new, more segmented and sophisticated offers and from the development of Internet services. Satellite is likely to enter these new markets at different levels of the value chain: Even if the satellite has demonstrated its capacity to fully serve the television, combinations with other networks may be necessary to address the new markets: at the consumer premises, Internet-related services will require a return path; at the backbone level, satellite becomes a component of a full telecommunications solution. This article focuses on the European market and proposes:

  15. The EMC of satellite power systems and DoD C-E systems

    Science.gov (United States)

    Atkinson, J. H.; Aasen, M. D.

    1980-01-01

    The solar power satellite (SPS) technical parameters that are needed to accurately assess the electromagnetic compatibility (EMC) between SPS systems and DoD communications-electronics (C-E) systems are identified and assessed. The type of electromagnetic interactions that could degrade the performance of C-E systems are described and the major military installations in the southwestern portions of CONUS where specially sensitive C-E systems are being used for combat training and evaluation are identified. Classes of C-E systems that are generally in the vicinity of these military installations are considered. The Technical parameters that govern the degree of compatibility of the SPS with these C-E systems, and some technical requirements that are necessary to ensure short-term and long-term EMC are identified.

  16. System Design of a S-band Solid-state Transmitter in Satellite-borne SAR

    Directory of Open Access Journals (Sweden)

    Zhao Hai-yang

    2014-06-01

    Full Text Available The system design of a S-band solid-state transmitter in satellite-borne SAR is introduced. A series of critical technologies, such as high reliability, environmental adaptability, and structure miniaturization, which are necessary in satellite applications, are analyzed and discussed. The technologies are experimentally verified at different periods. Multichannel combined technology is used for the transmitter, and the output peak power is more than 3 kW. Because of the high efficiency, small size, lightweight, and high power, it is especially applicable in small satellite platforms.

  17. Application of communications satellites to educational development. [technology utilization/information systems - bibliographies

    Science.gov (United States)

    Morgan, R. P.

    1975-01-01

    A summary of research is presented. The broad objectives of this interdisciplinary research effort were: (1) to assess the role of satellite communications as a means of improving education in the United States, as well as in less-developed areas of the world; (2) to generate basic knowledge which will aid in making rational decisions about satellite application in the field of education in the years ahead; (3) to devise systems and strategies for improving education; and (4) to educate individuals who will be knowledgeable about aspects of satellite communications policy which transcend any single discipline.

  18. System Design and In-orbit Verification of the HJ-1-C SAR Satellite

    Directory of Open Access Journals (Sweden)

    Zhang Run-ning

    2014-06-01

    Full Text Available HJ-1-C is a SAR satellite owned by the Chinese Environment and Natural Disaster Monitoring constellation, and works together with the optical satellites HJ-1-A/B for monitoring environment and natural disasters. In this paper, the system design and characteristics of the first Chinese civil SAR satellite are described. In addition, the interface relation between SAR payload and platform is studied. Meanwhile, the data transmission capability, attitude, power, and temperature control that support SAR imaging are reviewed. Finally, the corresponding in-orbit verification results are presented.

  19. Earth's thermal radiation sensors for attitude determination systems of small satellites

    Science.gov (United States)

    Vertat, I.; Linhart, R.; Masopust, J.; Vobornik, A.; Dudacek, L.

    2017-07-01

    Satellite attitude determination is a complex process with expensive hardware and software and it could consume the most of resources (volume, mass, electric power), especially of small satellites as CubeSats. Thermal radiation infrared detectors could be one of useful sensors for attitude determination systems in such small satellites. Nowadays, these sensors are widely used in contact-less thermometers and thermo-cameras resulting in a low-cost technology. On low Earth orbits the infrared thermal sensors can be utilized for coarse attitude determination against a relative warm and close Earth's globe.

  20. Clouds and the Earth's Radiant Energy System (CERES) Visualization Single Satellite Footprint (SSF) Plot Generator

    Science.gov (United States)

    Barsi, Julia A.

    1995-01-01

    The first Clouds and the Earth's Radiant Energy System (CERES) instrument will be launched in 1997 to collect data on the Earth's radiation budget. The data retrieved from the satellite will be processed through twelve subsystems. The Single Satellite Footprint (SSF) plot generator software was written to assist scientists in the early stages of CERES data analysis, producing two-dimensional plots of the footprint radiation and cloud data generated by one of the subsystems. Until the satellite is launched, however, software developers need verification tools to check their code. This plot generator will aid programmers by geolocating algorithm result on a global map.

  1. Spectrum and orbit conservation as a factor in future mobile satellite system design

    Science.gov (United States)

    Bowen, Robert R.

    1990-01-01

    Access to the radio spectrum and geostationary orbit is essential to current and future mobile satellite systems. This access is difficult to obtain for current systems, and may be even more so for larger future systems. In this environment, satellite systems that minimize the amount of spectrum orbit resource required to meet a specific traffic requirement are essential. Several spectrum conservation techniques are discussed, some of which are complementary to designing the system at minimum cost. All may need to be implemented to the limits of technological feasibility if network growth is not to be constrained because of the lack of available spectrum-orbit resource.

  2. Reusable Reentry Satellite (RRS) system design study: System cost estimates document

    Science.gov (United States)

    1991-01-01

    The Reusable Reentry Satellite (RRS) program was initiated to provide life science investigators relatively inexpensive, frequent access to space for extended periods of time with eventual satellite recovery on earth. The RRS will provide an on-orbit laboratory for research on biological and material processes, be launched from a number of expendable launch vehicles, and operate in Low-Altitude Earth Orbit (LEO) as a free-flying unmanned laboratory. SAIC's design will provide independent atmospheric reentry and soft landing in the continental U.S., orbit for a maximum of 60 days, and will sustain three flights per year for 10 years. The Reusable Reentry Vehicle (RRV) will be 3-axis stabilized with artificial gravity up to 1.5g's, be rugged and easily maintainable, and have a modular design to accommodate a satellite bus and separate modular payloads (e.g., rodent module, general biological module, ESA microgravity botany facility, general botany module). The purpose of this System Cost Estimate Document is to provide a Life Cycle Cost Estimate (LCCE) for a NASA RRS Program using SAIC's RRS design. The estimate includes development, procurement, and 10 years of operations and support (O&S) costs for NASA's RRS program. The estimate does not include costs for other agencies which may track or interface with the RRS program (e.g., Air Force tracking agencies or individual RRS experimenters involved with special payload modules (PM's)). The life cycle cost estimate extends over the 10 year operation and support period FY99-2008.

  3. Numerical modeling of a Global Navigation Satellite System in a general relativistic framework

    CERN Document Server

    Delva, P; Cadez, A

    2010-01-01

    In this article we model a Global Navigation Satellite System (GNSS) in a Schwarzschild space-time, as a first approximation of the relativistic geometry around the Earth. The closed time-like and scattering light-like geodesics are obtained analytically, describing respectively trajectories of satellites and electromagnetic signals. We implement an algorithm to calculate Schwarzschild coordinates of a GNSS user who receives proper times sent by four satellites, knowing their orbital parameters; the inverse procedure is implemented to check for consistency. The constellation of satellites therefore realizes a geocentric inertial reference system with no \\emph{a priori} realization of a terrestrial reference frame. We show that the calculation is very fast and could be implemented in a real GNSS, as an alternative to usual post-Newtonian corrections. Effects of non-gravitational perturbations on positioning errors are assessed, and methods to reduce them are sketched. In particular, inter-links between satelli...

  4. Cochannel and Adjacent-Channel Interference in Nonlinear Minimum-Shift-Keyed Satellite System

    Science.gov (United States)

    Yu, John

    1995-01-01

    The interference susceptibility of a serial-minimum-shift-keyed (SMSK) modulation system to an interfering signal transmitted through a satellite link with cascaded nonlinear elements was investigated through computer simulation. The satellite link evaluated in this study represented NASA's Advanced Communications Technology Satellite (ACTS) system. Specifically, nonlinear characteristics were used that had specified amplitude-modulation to amplitude-modulation and amplitude-modulation to phase-modulation transfer characteristics obtained from the actual ACTS hardware. Two measurement scenarios were analyzed: degradation of an MSK satellite link from cochannel interference and from adjacent-channel interference. Interference was evaluated in terms of the probability of bit error rate (BER) versus energy per bit over noise power density Eb/No.

  5. A new approach to design of quasi-isotropic antenna systems for satellite applications

    DEFF Research Database (Denmark)

    Schjær-Jacobsen, Hans; Hansen, J.E.

    1976-01-01

    The new approach considered takes into account the maximum error of the quasi-isotropic radiation pattern relative to the ideal pattern. A design example involving a spherical satellite with quarter wave monopoles is used to demonstrate the effectiveness of the new approach. An investigation...... is conducted concerning the minimax optimization of power radiation patterns. It is shown that the minimax objective represents a useful alternative to the isotropy concept in the design of quasi-isotropic antenna systems for satellite applications....

  6. A new approach to design of quasi-isotropic antenna systems for satellite applications

    DEFF Research Database (Denmark)

    Schjær-Jacobsen, Hans; Hansen, J.E.

    1976-01-01

    The new approach considered takes into account the maximum error of the quasi-isotropic radiation pattern relative to the ideal pattern. A design example involving a spherical satellite with quarter wave monopoles is used to demonstrate the effectiveness of the new approach. An investigation...... is conducted concerning the minimax optimization of power radiation patterns. It is shown that the minimax objective represents a useful alternative to the isotropy concept in the design of quasi-isotropic antenna systems for satellite applications....

  7. Satellite registration program: a decentralized system to meet customer needs.

    Science.gov (United States)

    Hutchins, J

    1991-01-01

    In summary, if you want to meet your patient, physician and ancillary service needs, then consider registration as a necessary transitional activity and then go about making it secondary to the reason the patient came for healthcare service. The complexities of data collection are for us to be concerned with, not the patient! Also, the physicians will appreciate your efforts on behalf of their patients. You, too, can have an effective Satellite Registration Program if you remember that flexibility, creativity and administrative support are essential to success! Good Luck!

  8. STRUCTURE OF THE SPANISH SYSTEM OF SATELLITE OF COMMUNICATIONS

    Directory of Open Access Journals (Sweden)

    F. Sacristán - Romero

    2007-04-01

    Full Text Available The objectives of satellites HISPASAT are oriented towards the search to satisfy necessities derived from the transport of television and radio signals. It tries the supplying of a basic and safe support of communications for the defence and security of the national territory, the creation of an infrastructure of channels for official networks, routes of data, restoration of connections, rural telephony. Also is wanted to foment the provision of television channels for the Hispanic community in the south and center of America and the broadcasting of services of television for people in general.

  9. Evaluating the Effect of Global Positioning System (GPS) Satellite Clock Error via GPS Simulation

    Science.gov (United States)

    Sathyamoorthy, Dinesh; Shafii, Shalini; Amin, Zainal Fitry M.; Jusoh, Asmariah; Zainun Ali, Siti

    2016-06-01

    This study is aimed at evaluating the effect of Global Positioning System (GPS) satellite clock error using GPS simulation. Two conditions of tests are used; Case 1: All the GPS satellites have clock errors within the normal range of 0 to 7 ns, corresponding to pseudorange error range of 0 to 2.1 m; Case 2: One GPS satellite suffers from critical failure, resulting in clock error in the pseudorange of up to 1 km. It is found that increase of GPS satellite clock error causes increase of average positional error due to increase of pseudorange error in the GPS satellite signals, which results in increasing error in the coordinates computed by the GPS receiver. Varying average positional error patterns are observed for the each of the readings. This is due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in GPS accuracy being location / time dependent. For Case 1, in general, the highest average positional error values are observed for readings with the highest PDOP values, while the lowest average positional error values are observed for readings with the lowest PDOP values. For Case 2, no correlation is observed between the average positional error values and PDOP, indicating that the error generated is random.

  10. New Projects Planed/launched By Cei Wg On Satellite Navigation Systems

    Science.gov (United States)

    Oszczak, S.; Manzoni, G.

    In the paper a short description of main projects on satellite positioning and naviga- tion in CEI countries is given. Special attention is devoted to the activity of members of Working Group on Satellite Navigation Systems. The projects in which they are involved and results of performed experiments can be specified as follows: - EGNOS positioning - the first results in CEI area, - application of various transmission tech- niques to diffusion of DGPS/RTK data from reference stations (SWIFT/DARC, RDS, radiobeacons, UHF transmission), - development of integrated GPS/INS methods for car navigation and GIS purposes, - development of software for integration of satellite vehicle position with numerical maps for car navigation, monitoring and acquisition of terrestrial data for GIS, - elaboration of method and software development for nav- igation and monitoring of aircraft during approaching and landing phase of flight, - elaboration of methods and software for integration of 3D satellite positions of user with Digital Terrain Model (DTM), - development of digital technology for bathy- metric survey with satellite positioning technique; mapping of shallow waters, lakes, rivers and inland water reservoirs, The recently planned studies and experiments cover land, marine and aircraft satellite navigation with EGNOS system in CEI countries. The project of extension of the EGNOS system to the Central and East European region is under preparation. Other important research is conducted on mapping of roads and rails tracks using integrated DGPS/INS techniques.

  11. Research of Multi-Agent System based satellite fault diagnosis technology

    Institute of Scientific and Technical Information of China (English)

    范显峰; 姜兴渭; 黄文虎; 谷吉海

    2002-01-01

    Following the theory of Multi-Agent System (MAS) and using series-wound structure and shunt-wound structure of Agents, the performance of Agent was improved to satisfy the need of satellite fault diagno-sis, and a tridimensional MAS model of satellite fault diagnosis was thus established for the MAS based planardiagnosis system, which decentralizes the whole diagnosing task into subtasks to be performed by different func-tional Agents to make the complicated fault diagnosis very simple and the diagnosis system more intelligent.This method improved the reliability and accuracy of diagnosis and made the maintenance and upgrading of thesatellite fault diagnosis system very easy as well.

  12. Reliability analysis and design of on-board computer system for small stereo mapping satellite

    Institute of Scientific and Technical Information of China (English)

    马秀娟; 曹喜滨; 马兴瑞

    2002-01-01

    The on-board computer system for a small satellite is required to be high in reliability, light in weight, small in volume and low in power consumption. This paper describes the on-board computer system with the advantages of both centralized and distributed systems, analyzes its reliability, and briefs the key techniques used to improve its reliability.

  13. Suggestion of EFS-small satellite system for impending earthquake forecast

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the IAF Congress '92 a multiple small satellite Earth observation system was put forward with sensors of visible and infrared spectrums. The system could shorten the revisiting period so that any place on the world could be observed twice a day. Now we extend the idea to the microwave remote sensing satellite system. The main purpose of the system is the impending forecast of earthquakes. According to the theory and long-time concrete practice of Qiang Zuji through the observation of temperature increase of the low layer of atmosphere and its moving trend caused by some sorts of radiation and gases released from Earth interior, an impending strong earthquake could be predicted in time. As the temperature increase is detected by thermo-infrared spectrum sensors on the meteorological satellites, the observation may be sometimes obstructed by cloud or rain. In the suggested system, mm-wave radiometers are used and those obstructions could be generally overcome.

  14. Research on the new type of multi-functional satellite system for space debris detection

    Science.gov (United States)

    Guo, Linghua; Fu, Qiang; Jiang, Huilin; Xu, Xihe

    2017-05-01

    With the rapid development of space exploration and utilization, orbital debris increases dramatically, leading to great threat to human space activities and spacecraft security. In this paper, a new type of multi-functional space debris satellite system (MSDS) was put forward, which shared main optical system, and possessed functions of multidimensional information detection, polarized remote sensing and high rate transmission. The MSDS system can meet the requirements of detection and identification for the small orbital debris which is 1000km faraway, as well as the requirements of the data transmission by 50 Mbps to 2.5 Gbps@200-1000 km. At the same time, by the method of satellite orbital maneuver and attitude adjusting, the orbital debris information that is real-time, complex and refined, allweather can be acquired and transmitted by the new system. Such new type of multifunctional satellite system can provide important and effective technology for international orbital debris detection.

  15. Effective communication : satellite system poised to improve information flow

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, R.

    2009-01-15

    This paper described a new satellite technology that can be used to transfer important information from offshore oil and gas facilities to decision-makers in distant onshore offices. Cascade Data Services (CDS), a subsidiary of British Columbia-based MDA Corporation, is developing a high-speed low-latency satellite information transfer service which has its roots in the Cascade Smallsat and Ionospheric Polar Explorer (CASSIOPE) mission scheduled for launch in 2009. The technology will enable customers to move thousands of gigabytes to and from anywhere on the planet on a daily basis. CASSIOPE received funding from the Canadian Space Agency and Technology Partnerships Canada. The first payload will be a suite of space science instruments known as the Enhanced Polar Outflow Probe (e-Pop) developed by researchers at the University of Calgary. The second payload will involve a demonstration of the digital courier service model and delivery of large digital data files. CDS has entered into an alliance with O3b Networks funded by Google Inc., Liberty Global Inc., and HSBC Principal Investments, among others. The technological development should improve the flow of information, making oil and gas operations in remote areas more efficient and help cut costs. 1 ref., 2 figs.

  16. Second-generation mobile satellite system. A conceptual design and trade-off study

    Science.gov (United States)

    Sue, M. K.; Park, Y. H.

    1985-01-01

    In recent years, interest has grown in the mobile satellite (MSAT) system, a satellite-based communications system capable of providing integrated voice and data services to a large number of users. To explore the potential of a commercial mobile satellite system (MSS) beyond the horizon of the first generation, using technologies of the 1990's and to assist MSAT-X in directing its efforts, a conceptual design has been performed for a second-generation system to be launched around the mid-1990's. The design goal is to maximize the number of satellite channels and/or minimize the overall life-cycle cost, subject to the constraint of utilizing a commercial satellite bus with minimum modifications. To provide an optimal design, a series of trade-offs are performed, including antenna sizing, feed configurations, and interference analysis. Interference is a serious problem for MSAT and often an overlapping feed design is required to reduce interbeam interference. The trade-off studies will show that a simple non-overlapping feed is sufficient for the second-generation system, thus avoiding the need for the complicated beam-forming network that is associated with the overlapping feed designs. In addition, a system that operates at L-band, an alternative frequency band that is being considered by some for possible MSAT applications, is also presented.

  17. Engineering Tools and Validation Test Beds for New Telecommunication Satellite Multimedia Systems

    Science.gov (United States)

    Foix, V.; Taisant, J.-Ph.; Piau, P.; Thomasson, L.

    2002-01-01

    Satellite telecommunication and broadcasting systems have to adapt to the major evolutions introduced by the emergence of new multimedia services distributed by terrestrial networks. This major adaptation of satellite telecommunication systems implies the use of new technologies and standards, on-board satellites and within the telecommunication ground segment. The deeper interaction between space and ground infrastructures induced by these evolutions also leads to additional system complexity. The definition, design and end-to-end validation of these satellite networks require dedicated engineering tools and validation test beds running the major elements of the telecommunication mission, e.g. on-board and ground equipment implementing the various protocols and algorithms used in the system. Through two programmes called respectively "Atelier Télécom du Futur" and "Multimedia System Validation Test Beds", CNES has been developing since early 2000 an advanced simulation tool and complementary test beds to support engineering activities and cover most of the end-to-end validation needs of these new satellite telecommunication multimedia systems. This communication aims to present the technical objectives, the logic which has led to propose several complementary means, their main characteristics and development status. To end up, the first results provided by these tools and test beds are presented.

  18. A Novel Method for Optimum Global Positioning System Satellite Selection Based on a Modified Genetic Algorithm.

    Science.gov (United States)

    Song, Jiancai; Xue, Guixiang; Kang, Yanan

    2016-01-01

    In this paper, a novel method for selecting a navigation satellite subset for a global positioning system (GPS) based on a genetic algorithm is presented. This approach is based on minimizing the factors in the geometric dilution of precision (GDOP) using a modified genetic algorithm (MGA) with an elite conservation strategy, adaptive selection, adaptive mutation, and a hybrid genetic algorithm that can select a subset of the satellites represented by specific numbers in the interval (4 ∼ n) while maintaining position accuracy. A comprehensive simulation demonstrates that the MGA-based satellite selection method effectively selects the correct number of optimal satellite subsets using receiver autonomous integrity monitoring (RAIM) or fault detection and exclusion (FDE). This method is more adaptable and flexible for GPS receivers, particularly for those used in handset equipment and mobile phones.

  19. Advanced spacecraft tracking techniques using the Tracking and Data Relay Satellite System /TDRSS/

    Science.gov (United States)

    Teles, J.; Ayres, C.

    1977-01-01

    The TDRSS will consist initially of two geosynchronous satellites and a common ground station at White Sands, New Mexico. According to current schedules, operations are to begin in November 1980. The overall TDRSS will provide high and low bit-rate telemetry, commands, and satellite-to-satellite tracking services. Each Tracking and Data Relay Satellite (TDRS) will have four antenna systems for NASA use. The common ground station at White Sands will have three 18-meter K-band antennas. The tracking equipment at the ground station is required to meet the following specifications: (1) 0.1-radian root-mean-square (rms) phase noise on nondestruct Doppler measurements; (2) 10-nanosecond rms range noise; (3) 50-nanosecond maximum systematic range error. Attention is given to two-way range and Doppler measurements, the bilateration tracking of TDRS, and an experiment using differenced one-way Doppler measurements.

  20. An advanced generation land mobile satellite system and its critical technologies

    Science.gov (United States)

    Naderi, F.

    1982-01-01

    A conceptual design for a Land Mobile Satellite System (LMSS) for the 1990s is presented. LMSS involves small tranceivers accessing satellites directly, with ground reception through small car-top antennas. The satellite would have a large antenna and blanket coverage areas in the UHF. The call may originate from a home, be carried by wire to a gateway, transmitted to satellite on the S-band, converted to UHF on the satellite, and transmitted to the vehicle. The system design is constrained by the number of users in an area during the busiest hours, Shuttle storage, controllability factors, and the total area served. A 55-m antenna has been selected, with 87 spot beams and two 10 MHz UHF bands in the 806-890 MHz band. A 17 dB interbeam isolation level is required, implying that sufficient sub-bands can be generated to assure 8265 total channels. The mobile satellite (MSAT) would have an 83 m mast lower segment, a 34 m upper segment, and a second, 10 m antenna made of a deployable mesh. Various antenna function modes are considered.

  1. Environmental assessment for the satellite power system concept development and evaluation program-electromagnetic systems compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Davis, K A; Grant, W B; Morrison, E L; Juroshek, J R

    1981-01-01

    The EMC analysis addressed only the direct effects of electromagnetic emissions from the SPS on other technological systems. Emissions were defined quite broadly, including not only those from the microwave system, but also thermal blackbody emission and scattered sunlight from the satellite. The analysis is based on the design for an SPS as described in the Reference System Report and some quantitative conclusions, e.g., ranges from rectenna sites at which effects are expected are specific to that design. The methodology and qualitative conclusions, however, apply to an SPS concept using microwave power transmission. Quantitative conclusions have been obtained parametrically and can be adjusted as SPS designs change. The electromagnetic environment that the Reference System would produce, and in which other systems would have to function, is described. As an early part of the EMC Assessment, the problems expected for a hypothetical rectenna site, in the Mojave Desert of southern California, were analyzed in detail. This effort provided an initial quantitative indication of the scope of potential EMC problems and indicated the importance of EMC considerations in rectenna site selection. The results of this analysis are presented. The effects of SPS microwave emissions on important categories of electronic systems and equipment are summarized, with many examples of test results and demonstrated techniques for mitigation of problems encountered. SPS effects on other satellite systems are presented. Astronomical research frequently involves measurement of extremely low levels of electromagnetic radiation and is thus very susceptible to interference. The concerns of both radio astronomy with microwave emissions from SPS and optical astronomy with sunlight scattered from SPS spacecraft are discussed. Summaries of mitigation techniques, cost estimates, and conclusions are presented. (WHK)

  2. Dynamical friction and scratches of orbiting satellite galaxies on host systems

    CERN Document Server

    Ogiya, Go

    2015-01-01

    We study the dynamical response of extended systems, hosts, to smaller systems, satellites, orbiting around the hosts using extremely high-resolution N-body simulations with up to one billion particles. This situation corresponds to minor mergers which are ubiquitous in the scenario of hierarchical structure formation in the universe. According to Chandrasekhar (1943), satellites create density wakes along the orbit and the wakes cause a deceleration force on satellites, i.e. dynamical friction. This study proposes an analytical model to predict the dynamical response of hosts in the density distribution and finds not only traditional wakes but also mirror images of over- and underdensities centered on the host. Controlled N-body simulations with high resolutions verify the predictions of the analytical model directly. We apply our analytical model to the expected dynamical response of nearby interacting galaxy pairs, the Milky Way - Large Magellanic Cloud system and the M31 - M33 system.

  3. Dynamical friction and scratches of orbiting satellite galaxies on host systems

    Science.gov (United States)

    Ogiya, Go; Burkert, Andreas

    2016-04-01

    We study the dynamical response of extended systems, hosts, to smaller systems, satellites, orbiting around the hosts using extremely high-resolution N-body simulations with up to one billion particles. This situation corresponds to minor mergers which are ubiquitous in the scenario of hierarchical structure formation in the universe. According to Chandrasekhar, satellites create density wakes along the orbit and the wakes cause a deceleration force on satellites, i.e. dynamical friction. This study proposes an analytical model to predict the dynamical response of hosts as reflected in their density distribution and finds not only traditional wakes but also mirror images of over- and underdensities centred on the host. Our controlled N-body simulations with high resolutions verify the predictions of the analytical model. We apply our analytical model to the expected dynamical response of nearby interacting galaxy pairs, the Milky Way-Large Magellanic Cloud system and the M31-M33 system.

  4. Preliminary design of a satellite observation system for Space Station Freedom

    Science.gov (United States)

    Cabe, Greg (Editor); Gallagher, Chris; Wilson, Brian; Rehfeld, James; Maurer, Alexa; Stern, Dan; Nualart, Jaime; Le, Xuan-Trang

    1992-01-01

    Degobah Satellite Systems (DSS), in cooperation with the University Space Research Association (USRA), NASA - Johnson Space Center (JSC), and the University of Texas, has completed the preliminary design of a satellite system to provide inexpensive on-demand video images of all or any portion of Space Station Freedom (SSF). DSS has narrowed the scope of the project to complement the work done by Mr. Dennis Wells at Johnson Space Center. This three month project has resulted in completion of the preliminary design of AERCAM, the Autonomous Extravehicular Robotic Camera, detailed in this design report. This report begins by providing information on the project background, describing the mission objectives, constraints, and assumptions. Preliminary designs for the primary concept and satellite subsystems are then discussed in detail. Included in the technical portion of the report are detailed descriptions of an advanced imaging system and docking and safing systems that ensure compatibility with the SSF. The report concludes by describing management procedures and project costs.

  5. A simple ship-borne antenna stabilizer for limited area maritime satellite communication systems

    Science.gov (United States)

    Satoh, K.; Nakamae, M.; Mishima, H.

    1984-10-01

    This paper deals with a simple ship-borne antenna stabilizer for use in limited area multi-beam maritime satellite communication systems. A limited area system with high satellite e.i.r.p. is expected to be a more economical satellite system than a global system, because a low-gain ship-borne antenna and a simplified antenna stabilizer can be used. An optimum configuration is proposed for small size and low cost pendulum-type antenna stabilizers which are suitable for low gain ship-borne antennas. Also, a performance evaluation of the stabilizers is discussed using a statistical analysis of ship motion characteristics. Furthermore, fading characteristics of received signal strength due to antenna off-beam fluctuation and sea surface random reflection are experimentally evaluated.

  6. SUMO/FREND: vision system for autonomous satellite grapple

    Science.gov (United States)

    Obermark, Jerome; Creamer, Glenn; Kelm, Bernard E.; Wagner, William; Henshaw, C. Glen

    2007-04-01

    SUMO/FREND is a risk reduction program for an advanced servicing spacecraft sponsored by DARPA and executed by the Naval Center for Space Technology at the Naval Research Laboratory in Washington, DC. The overall program will demonstrate the integration of many techniques needed in order to autonomously rendezvous and capture customer satellites at geosynchronous orbits. A flight-qualifiable payload is currently under development to prove out challenging aspects of the mission. The grappling process presents computer vision challenges to properly identify and guide the final step in joining the pursuer craft to the customer. This paper will provide an overview of the current status of the project with an emphasis on the challenges, techniques, and directions of the machine vision processes to guide the grappling.

  7. Moscow State University near-Earth radiation monitoring satellite system: current status and development

    Science.gov (United States)

    Panasyuk, Mikhail

    2016-07-01

    Radiation measurements using instruments have been designed and manufacturing in the Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University and installed onboard different satellites,i.e. LEO -"Meteor", ISS, GPS - GLONASS, GEO - "Electro" are presented as a basis of radiation monitoring system for control of radiation condition with a goal for to decrease radiation risk of spacecraft's damage on different orbits. Development of this system including radiation measurements onboard "Lomonosov"(LEO) satellite will be presented as well together with future project of multispacecraft LEO system for radiation monitoring.

  8. A Piecewise Affine Hybrid Systems Approach to Fault Tolerant Satellite Formation Control

    DEFF Research Database (Denmark)

    Grunnet, Jacob Deleuran; Larsen, Jesper Abildgaard; Bak, Thomas

    2008-01-01

    In this paper a procedure for modelling satellite formations   including failure dynamics as a piecewise-affine hybrid system is   shown. The formulation enables recently developed methods and tools   for control and analysis of piecewise-affine systems to be applied   leading to synthesis of fault...... tolerant controllers and analysis of   the system behaviour given possible faults.  The method is   illustrated using a simple example involving two satellites trying   to reach a specific formation despite of actuator faults occurring....

  9. A Piecewise Affine Hybrid Systems Approach to Fault Tolerant Satellite Formation Control

    DEFF Research Database (Denmark)

    Grunnet, Jacob Deleuran; Larsen, Jesper Abildgaard; Bak, Thomas

    2008-01-01

    In this paper a procedure for modelling satellite formations   including failure dynamics as a piecewise-affine hybrid system is   shown. The formulation enables recently developed methods and tools   for control and analysis of piecewise-affine systems to be applied   leading to synthesis of fault...... tolerant controllers and analysis of   the system behaviour given possible faults.  The method is   illustrated using a simple example involving two satellites trying   to reach a specific formation despite of actuator faults occurring....

  10. Telecommunication service markets through the year 2000 in relation to millimeter wave satellite systems

    Science.gov (United States)

    Stevenson, S. M.

    1979-01-01

    NASA is currently conducting a series of millimeter wave satellite system market studies to develop 30/20 GHz satellite system concepts that have commercial potential. Four contractual efforts were undertaken: two parallel and independent system studies and two parallel and independent market studies. The marketing efforts are focused on forecasting the total domestic demand for long haul telecommunications services for the 1980-2000 period. Work completed to date and reported in this paper include projections of: geographical distribution of traffic; traffic volume as a function of urban area size; and user identification and forecasted demand.

  11. Pre-Launch Radiometric Performance Characterization of the Advanced Technology Microwave Sounder on the Joint Polar Satellite System-1 Satellite

    Science.gov (United States)

    Smith, Craig K.; Kim, Edward; Leslie, R. Vincent; Lyu, Joseph; McCormick, Lisa M.; Anderson, Kent

    2017-01-01

    The Advanced Technology Microwave Sounder (ATMS) is a space-based, cross-track radiometer for operational atmospheric temperature and humidity sounding, utilizing 22 channels over a frequency range from 23 to 183 gigahertz. The ATMS for the Joint Polar Satellite System-1 has undergone two rounds of re-work in 2014-2015 and 2016, following performance issues discovered during and following thermal vacuum chamber (TVAC) testing at the instrument and observatory level. Final shelf-level testing, including measurement of pass band characteristics and spectral response functions, was completed in December 2016. Final instrument-level TVAC testing and calibration occurred during February 2017. Here we will describe the instrument-level TVAC calibration process, and illustrate with results from the final TVAC calibration effort.

  12. Customer premise service study for 30/20 GHz satellite system

    Science.gov (United States)

    Milton, R. T.; Ross, D. P.; Harcar, A. R.; Freedenberg, P.; Schoen, D.

    1983-01-01

    Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band.

  13. Ocean tidal dissipation and its role in solar system satellite evolution

    Science.gov (United States)

    Chen, Erinna M.

    The history of satellites in the Solar System is quite diverse. For example, satellites like Io and Enceladus exhibit active volcanism currently, while satellites like Ganymede and Tethys show signs of geologic activity in the deep past, but not at present. The energy dissipated by tides has been identified as a major heat source for satellites, but calculations for satellite tidal dissipation primarily focus on dissipation in a solid layer, such as the ice shell. An exciting discovery of the NASA spacecraft missions Galileo and Cassini is that global-scale, deep, liquid water oceans are present on many of the outer Solar System satellites. Tyler (2008) suggested that tidal dissipation due to flow in these oceans could potentially be a significant and previously neglected source of heat. However, a critical free parameter in Tyler's model is the effective turbulent viscosity in the ocean. The value of the effective viscosity is unconstrained and because the amount of tidal dissipation scales with this parameter, the amount of ocean tidal dissipation is also unconstrained. In order to address this uncertainty, we developed a numerical model that solves the shallow-water equations on a spherical shell and includes a nonlinear bottom friction parameterization for viscous dissipation. The bottom friction coefficient has a well-established value in the terrestrial literature; however, the nonlinearity of this term in the equations of motion make the model far more computationally expensive than a model that includes turbulent viscosity. Thus, we provide numerically-derived scalings that map the bottom friction coefficient and satellite parameters to an equivalent effective turbulent viscosity. Because tides depend on both the thermal structure of a satellite as well as characteristics of the satellite's orbit, models that couple thermal and orbital evolution are required to understand the history of a satellite. We use our numerically-derived scalings to adapt a coupled

  14. Optimality of incompletely measurable active and passive attitude control systems. [for satellites

    Science.gov (United States)

    Schiehlen, W.; Popp, K.

    1973-01-01

    Passive attitude control systems and active systems with incomplete state measurements are only suboptimal systems in the sense of optimal control theory, since optimal systems require complete state measurements or state estimations. An optimal system, then, requires additional hardware (especially in the case of flexible spacecraft) which results in higher costs. Therefore, it is a real engineering problem to determine how much an optimal system exceeds the suboptimal system, or in other words, what is the suboptimal system's degree of optimality. The problem will be treated in three steps: (1) definition of the degree of optimality for linear, time-invariant systems; (2) a computation method using the quadratic cost functional; (3) application to a gravity-gradient stabilized three-body satellite and a spinning flexible satellite.

  15. Observation of new satellites in Cs-Ar system using resonance ionization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M.H.; Hurst, G.S.; Payne, M.G.; Young, J.P.

    1978-07-31

    The absorption line shape of Cs-Ar system is recorded using two-photon ionization of the system with Cs(7P) as an intermediate state. New satellite structures in the wings of Cs(7P) are observed which were not resolved in previous absorption measurements. Also the absolute absorption cross section in the blue wing is measured.

  16. System for electronic transformation and geographic correlation of satellite television information. [cloud cover photography

    Science.gov (United States)

    Dubenskiy, V. P.; Nemkovskiy, B. L.; Rodionov, B. N.

    1974-01-01

    An electronic transformation and correlation system has been developed for the Meteor space weather system which provides transformation and scaling of the original picture, accounts for satellite flight altitude and inclinations of the optical axes of the transmitting devices, and simultaneously superposes the geographical coordinate grid on the transformed picture.

  17. 17th East European Conference on Advances in Databases and Information Systems and Associated Satellite Events

    CERN Document Server

    Cerquitelli, Tania; Chiusano, Silvia; Guerrini, Giovanna; Kämpf, Mirko; Kemper, Alfons; Novikov, Boris; Palpanas, Themis; Pokorný, Jaroslav; Vakali, Athena

    2014-01-01

    This book reports on state-of-art research and applications in the field of databases and information systems. It includes both fourteen selected short contributions, presented at the East-European Conference on Advances in Databases and Information Systems (ADBIS 2013, September 1-4, Genova, Italy), and twenty-six papers from ADBIS 2013 satellite events. The short contributions from the main conference are collected in the first part of the book, which covers a wide range of topics, like data management, similarity searches, spatio-temporal and social network data, data mining, data warehousing, and data management on novel architectures, such as graphics processing units, parallel database management systems, cloud and MapReduce environments. In contrast, the contributions from the satellite events are organized in five different parts, according to their respective ADBIS satellite event: BiDaTA 2013 - Special Session on Big Data: New Trends and Applications); GID 2013 – The Second International Workshop ...

  18. Spacecraft flight control system design selection process for a geostationary communication satellite

    Science.gov (United States)

    Barret, C.

    1992-01-01

    The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Now, as we launch the Mars observer and the Cassini spacecraft, stability and control have become higher priorities. The flight control system design selection process is reviewed using as an example a geostationary communication satellite which is to have a life expectancy of 10 to 14 years. Disturbance torques including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques are assessed to quantify the disturbance environment so that the required compensating torque can be determined. Then control torque options, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, nutation dampers, inertia augmentation techniques, three-axis control, reactions control system (RCS), and RCS sizing, are considered. A flight control system design is then selected and preliminary stability criteria are met by the control gains selection.

  19. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

    Science.gov (United States)

    Carter, P.; Beach, M. A.

    1993-01-01

    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  20. Computational methodology to predict satellite system-level effects from impacts of untrackable space debris

    Science.gov (United States)

    Welty, N.; Rudolph, M.; Schäfer, F.; Apeldoorn, J.; Janovsky, R.

    2013-07-01

    This paper presents a computational methodology to predict the satellite system-level effects resulting from impacts of untrackable space debris particles. This approach seeks to improve on traditional risk assessment practices by looking beyond the structural penetration of the satellite and predicting the physical damage to internal components and the associated functional impairment caused by untrackable debris impacts. The proposed method combines a debris flux model with the Schäfer-Ryan-Lambert ballistic limit equation (BLE), which accounts for the inherent shielding of components positioned behind the spacecraft structure wall. Individual debris particle impact trajectories and component shadowing effects are considered and the failure probabilities of individual satellite components as a function of mission time are calculated. These results are correlated to expected functional impairment using a Boolean logic model of the system functional architecture considering the functional dependencies and redundancies within the system.

  1. Neptune's small satellites

    Science.gov (United States)

    Thomas, P.

    1992-04-01

    The small satellites of Neptune and other planets discovered during the Voyager 2 mission are discussed in terms of their composition and relationship to the planetary systems. The satellite Proteus is described in terms of its orbit, five other satellites are described, and they are compared to ther small satellites and systems. Neptune's satellites are hypothesized to be related to the ring system, and the satellite Galatea is related to the confinement of the rings.

  2. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System

    Directory of Open Access Journals (Sweden)

    Shau-Shiun Jan

    2016-05-01

    Full Text Available The Chinese BeiDou navigation satellite system (BDS aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA methods, three signal quality analysis (SQA methods, and four measurement quality analysis (MQA methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region.

  3. Keck Adaptive Optics Observations of Neptune's Ring and Satellite Keck Adaptive Optics Observations of Neptune's Ring and Satellite System

    Science.gov (United States)

    de Pater, I.; Gibbard, S.; Martin, S.; Marchis, F.; Roe, H. G.; Macintosh, B.

    2003-05-01

    We observed Neptune, its satellites and ring system on UT 27 and 28 July 2002, with NIRC2 on the 10-m Keck II telescope at 2.2 micron. The total field of view was 10". Each image was integrated for 1 minute; on the first day we had a total of 18 frames, and 33 images on the second day, each spread out over a time interval of 1-2 hours. The complete Adams and Le Verrier rings are visible on each day, after combining all images. In the regions away from the ring arcs, we find that the Le Verrier ring is brighter (up to 20-40%) than the Adams ring. The ring arcs are readily apparent in combinations of the data that take into account Keplerian motion. The ring arc positions are in close agreement with Nicholson et al's (1995) result, as in HST/NICMOS images (Dumas et al. 2002). The Egalite ring has broadened even more since observed with HST/NICMOS in 1998, and is clearly the brightest ring arc. Liberte has decreased in intensity since Voyager and NICMOS. Courage was extremely faint in our images. The satellites Proteus, Larissa, Galatea and Despina are easily seen on individual frames. Thalassa is detected after properly shifting/rotating and adding several frames. This is the first time since the Voyager flybys that Thalassa is detected. Preliminary astrometric measurements suggest the satellites Larissa and Galathea, relative to Proteus, to be off from their nominal (JPL Horizons) positions by 0.3", and Despina by 0.1". Recent results indicate that Proteus is offset by 0.1" compared to Triton (Martins et al. 2003). Preliminary I/F values are 0.06 for Proteus, 0.045 for Larissa and Galatea, and 0.03 for Despina and Thalassa. These observations were supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783

  4. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Science.gov (United States)

    2010-10-01

    ... service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  5. The C3PO project: a laser communication system concept for small satellites

    Science.gov (United States)

    d'Humières, Benoît; Esmiller, Bruno; Gouy, Yann; Steck, Emilie; Quintana, Crisanto; Faulkner, Graham; O'Brien, Dominic; Sproll, Fabian; Wagner, Paul; Hampf, Daniel; Riede, Wolfgang; Salter, Michael; Wang, Qin; Platt, Duncan; Jakonis, Darius; Piao, Xiaoyu; Karlsson, Mikael; Oberg, Olof; Petermann, Ingemar; Michalkiewicz, Aneta; Krezel, Jerzy; Debowska, Anna; Thueux, Yoann

    2017-02-01

    The satellite market is shifting towards smaller (micro and nanosatellites), lowered mass and increased performance platforms. Nanosatellites and picosatellites have been used for a number of new, innovative and unique payloads and missions. This trend requires new concepts for a reduced size, a better performance/weight ratio and a reduction of onboard power consumption. In this context, disruptive technologies, such as laser-optical communication systems, are opening new possibilities. This paper presents the C3PO1 system, "advanced Concept for laser uplink/ downlink CommuniCation with sPace Objects", and the first results of the development of its key technologies. This project targets the design of a communications system that uses a ground-based laser to illuminate a satellite, and a Modulating Retro-Reflector (MRR) to return a beam of light modulated by data to the ground. This enables a downlink, without a laser source on the satellite. This architecture suits well to small satellite applications so as high data rates are potentially provided with very low board mass. C3PO project aims to achieve data rates of 1Gbit/s between LEO satellites and Earth with a communication payload mass of less than 1kilogram. In this paper, results of the initial experiments and demonstration of the key technologies will be shown.

  6. Performance analysis of GPS augmentation using Japanese Quasi-Zenith Satellite System

    Science.gov (United States)

    Wu, F.; Kubo, N.; Yasuda, A.

    2004-01-01

    The current GPS satellite constellation provides limited availability and reliability for a country like Japan where mountainous terrain and urban canyons do not allow a clear skyline to the horizon. At present, the Japanese Quasi-Zenith Satellite System (QZSS) is under investigation through a government-private sector cooperation. QZSS is considered a multi-mission satellite system, as it is able to provide communication, broadcasting and positioning services for mobile users in a specified region with high elevation angle. The performance of a Global Navigation Satellite System (GNSS) can be quantified by availability, accuracy, reliability and integrity. This paper focuses on availability, accuracy and reliability of GPS with and without augmentation using QZSS. The availability, accuracy and reliability of GPS only and augmented GPS using QZSS in the Asia-Pacific and Australian area is studied by software simulation. The simulation results are described by the number of visible satellites as a measure of availability, geometric dilution of precision as a measure of accuracy and minimal detectable bias, and bias-to-noise rate as a measure of reliability, with spatial and temporal variations. It is shown that QZSS does not only improve the availability and accuracy of GPS positioning, but also enhances the reliability of GPS positioning in Japan and its neighboring area.

  7. Optimization of Power Allocation for Multiusers in Multi-Spot-Beam Satellite Communication Systems

    Directory of Open Access Journals (Sweden)

    Heng Wang

    2014-01-01

    Full Text Available In recent years, multi-spot-beam satellite communication systems have played a key role in global seamless communication. However, satellite power resources are scarce and expensive, due to the limitations of satellite platform. Therefore, this paper proposes optimizing the power allocation of each user in order to improve the power utilization efficiency. Initially the capacity allocated to each user is calculated according to the satellite link budget equations, which can be achieved in the practical satellite communication systems. The problem of power allocation is then formulated as a convex optimization, taking account of a trade-off between the maximization of the total system capacity and the fairness of power allocation amongst the users. Finally, an iterative algorithm based on the duality theory is proposed to obtain the optimal solution to the optimization. Compared with the traditional uniform resource allocation or proportional resource allocation algorithms, the proposed optimal power allocation algorithm improves the fairness of power allocation amongst the users. Moreover, the computational complexity of the proposed algorithm is linear with both the numbers of the spot beams and users. As a result, the proposed power allocation algorithm is easy to be implemented in practice.

  8. System capacity and economic modeling computer tool for satellite mobile communications systems

    Science.gov (United States)

    Wiedeman, Robert A.; Wen, Doong; Mccracken, Albert G.

    1988-01-01

    A unique computer modeling tool that combines an engineering tool with a financial analysis program is described. The resulting combination yields a flexible economic model that can predict the cost effectiveness of various mobile systems. Cost modeling is necessary in order to ascertain if a given system with a finite satellite resource is capable of supporting itself financially and to determine what services can be supported. Personal computer techniques using Lotus 123 are used for the model in order to provide as universal an application as possible such that the model can be used and modified to fit many situations and conditions. The output of the engineering portion of the model consists of a channel capacity analysis and link calculations for several qualities of service using up to 16 types of earth terminal configurations. The outputs of the financial model are a revenue analysis, an income statement, and a cost model validation section.

  9. Preliminary environmental assessment for the Satellite Power System (SPS). Revision 1. Volume 2. Detailed assessment

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    The Department of Energy (DOE) is considering several options for generating electrical power to meet future energy needs. The satellite power system (SPS), one of these options, would collect solar energy through a system of satellites in space and transfer this energy to earth. A reference system has been described that would convert the energy to microwaves and transmit the microwave energy via directive antennas to large receiving/rectifying antennas (rectennas) located on the earth. At the rectennas, the microwave energy would be converted into electricity. The potential environmental impacts of constructing and operating the satellite power system are being assessed as a part of the Department of Energy's SPS Concept Development and Evaluation Program. This report is Revision I of the Preliminary Environmental Assessment for the Satellite Power System published in October 1978. It refines and extends the 1978 assessment and provides a basis for a 1980 revision that will guide and support DOE recommendations regarding future SPS development. This is Volume 2 of two volumes. It contains the technical detail suitable for peer review and integrates information appearing in documents referenced herein. The key environmental issues associated with the SPS concern human health and safety, ecosystems, climate, and electromagnetic systems interactions. In order to address these issues in an organized manner, five tasks are reported: (I) microwave-radiation health and ecological effects; (II) nonmicrowave health and ecological effectss; (III) atmospheric effects; (IV) effects on communication systems due to ionospheric disturbance; and (V) electromagnetic compatibility. (WHK)

  10. A System to Detect Residential Area in Multispectral Satellite Images

    Directory of Open Access Journals (Sweden)

    Seyfallah Bouraoui

    2011-11-01

    Full Text Available In this paper, we propose a new solution to extract complex structures from High-Resolution (HR remote-sensing images. We propose to represent shapes and there relations by using region adjacency graphs. They are generated automatically from the segmented images. Thus, the nodes of the graph represent shape like houses, streets or trees, while arcs describe the adjacency relation between them. In order to be invariant to transformations such as rotation and scaling, the extraction of objects of interest is done by combining two techniques: one based on roof color to detect the bounding boxes of houses, and one based on mathematical morphology notions to detect streets. To recognize residential areas, a model described by a regular language is built. The detection is achieved by looking for a path in the region adjacency graph, which can be recognized as a word belonging to the description language. Our algorithm was tested with success on images from the French satellite SPOT 5 representing the urban area of Strasbourg (France at different spatial resolution.

  11. The geo-control system for station keeping and colocation of geostationary satellites

    Science.gov (United States)

    Montenbruck, O.; Eckstein, M. C.; Gonner, J.

    1993-01-01

    GeoControl is a compact but powerful and accurate software system for station keeping of single and colocated satellites, which has been developed at the German Space Operations Center. It includes four core modules for orbit determination (including maneuver estimation), maneuver planning, monitoring of proximities between colocated satellites, and interference and event prediction. A simple database containing state vector and maneuver information at selected epochs is maintained as a central interface between the modules. A menu driven shell utilizing form screens for data input serves as the central user interface. The software is written in Ada and FORTRAN and may be used on VAX workstations or mainframes under the VMS operating system.

  12. A CDMA architecture for a Ka-band Personal Access Satellite System

    Science.gov (United States)

    Motamedi, Masoud; Sue, Miles K.

    1990-01-01

    A Code Division Multiple Access (CDMA) architecture is currently being studied for use in a Ka-band Personal Access Satellite System (PASS). The complete architecture consisting of block diagrams of the user terminal, the supplier station, the network management center, and the satellite is described along with the access methods and frequency/time plans. The complexity of developing this system using the CDMA architecture is compared to that of a Frequency Division Multiple Access (FDMA) architecture. The inherent advantages and disadvantages of the two architectures are compared and their respective capacities are discussed.

  13. The FODA-TDMA satellite access scheme - Presentation, study of the system, and results

    Science.gov (United States)

    Celandroni, Nedo; Ferro, Erina

    1991-12-01

    A description is given of FODA-TDMA, a satellite access scheme designed for mixed traffic. The study of the system is presented and the choice of some parameters is justified. A simplified analytic solution is found, describing the steady-state behavior of the system. Some results of the simulation tests for an already existing hardware environment are also presented for the channel speeds of 2 and 8 Mb/s, considering both the stationary and the transient cases. The results of the experimentation at 2 Mb/s on the satellite Eutelsat-F2 are also presented and compared with the results of the simulation.

  14. Impact-driven ice loss in outer Solar System satellites: Consequences for the Late Heavy Bombardment

    Science.gov (United States)

    Nimmo, F.; Korycansky, D. G.

    2012-05-01

    We use recent hydrodynamical results (Kraus, R.G., Senft, L.G., Stewart, S.S. [2011]. Icarus, 214, 724-738) for the production of water vapor by hypervelocity impacts on ice targets to assess which present-day major satellites of Jupiter, Saturn, and Uranus would have lost mass due to impact vaporization during an era of massive bombardment similar to the Late Heavy Bombardment in the inner Solar System. Using impactor populations suggested by recent work (Charnoz, S., Morbidelli, A., Dones, L., Salmon, J. [2009]. Icarus, 199, 413-428; Barr, A.C., Canup, R.M. [2010]. Nat. Geosci., 3, 164-167), we find that several satellites would have lost all their HO; we suggest that the most likely resolution of this paradox is that either the LHB delivered ≈10 times less mass to the outer Solar System than predicted by the standard Nice Model, or that the inner satellites formed after the LHB.

  15. Long-term evolution of the inclined geosynchronous orbit in Beidou Navigation Satellite System

    Science.gov (United States)

    Tang, Jingshi; Hou, Xiyun; Liu, Lin

    2017-02-01

    China's Beidou Navigation Satellite System (BDS), unlike other navigation satellite systems, uses several inclined geosynchronous orbits (IGSO) to enhance the accuracy of regional or global navigation. In order to maintain a safe space environment in the vicinity of its operational orbit, it is necessary that the decommissioned satellites be well disposed of. To understand the underlying dynamics that affect the BDS IGSO, we study this problem from two aspects. In this paper, we first theoretically analyze the problem using the simplified models with 1 and 2 degrees of freedoms (1-/2-dof). Then we extensively investigate the numerically propagated orbits for 200 and 1000 years, applying the results from these simplified models and seeking proper explanations for the underlying dynamics. We especially focus on the eccentricity evolution, which is a major concern regarding the collision hazard. We expect to understand the underlying dynamics governing the long-term evolution of BDS IGSO and gain helpful insight into future disposal strategies.

  16. Use of a geosynchronous satellite within the SARSAT/COSPAS system

    Science.gov (United States)

    Goudy, P.; Ludwig, D.; Trudell, B.

    1982-01-01

    Operational characteristics of combined LEO SARSAT/COSPAS and GEO spacecraft for localization of aircraft and seacraft emitting distress signals are described. Although 121.5 MHz capability is now included in all SARSAT/COSPAS satellites, limitations on the number of simultaneous signals which can be processed at that frequency due to atmospheric noise indicates the employment of the 406 MHz band. Additionally, the necessity for on-board storage for later transmission when the satellites are in a favorable position is leading to the implementation of GEO stationed relays for real-time transmission and processing of distress signals. Six NOAA spacecraft and two Soviet satellites are planned, with a completed system offering high detection probability, position location, worldwide coverage, coded messages, and high capacity (406 MHz). A significant factor in use of a GEO relay system is noted to be the signal to noise temperature of the repeater.

  17. R&D of a Next Generation LEO System for Global Multimedia Mobile Satellite Communications

    Science.gov (United States)

    Morikawa, E.; Motoyoshi, S.; Koyama, Y.; Suzuki, R.; Yasuda, Y.

    2002-01-01

    Next-generation LEO System Research Center (NeLS) was formed in the end of 1997 as a research group under the Telecommunications Advancement Organization of Japan, in cooperation with the telecommunications operators, manufacturers, universities and governmental research organization. The aim of this project is to develop new technology for global multimedia mobile satellite communications services with a user data rate around 2Mbps for handy terminals. component of the IMT-2000, and the second generation of the big-LEO systems. In prosecuting this project, two-phase approach, phase 1 and phase 2, is considered. Phase 1 is the system definition and development of key technologies. In Phase 2, we plan to verify the developed technology in Phase 1 on space. From this year we shifted the stage to Phase 2, and are now developing the prototype of on-board communication systems for flight tests, which will be planed at around 2006. The satellite altitude is assumed to be 1200 km in order to reduce the number of satellites, to avoid the Van Allen radiation belts and to increase the minimum elevation angle. Ten of the circular orbits with 55 degree of inclination are selected to cover the earth surface from -70 to 70 degree in latitude. 12 satellites are positioned at regular intervals in each orbit. In this case, the minimum elevation angle from the user terminal can be keep more than 20 degree for the visibility of the satellite, and 15 degree for simultaneous visibility of two satellites. Then, NeLS Research Center was focusing on the development of key technologies as the phase 1 project. Four kinds of key technologies; DBF satellite antenna, optical inter-satellite link system, satellite network technology with on-board ATM switch and variable rate modulation were selected. Satellite Antenna Technology: Development of on-board direct radiating active phased array antenna with digital beam forming technology would be one of the most important breakthroughs for the

  18. Ionizing radiation risks to satellite power systems (SPS) workers

    Energy Technology Data Exchange (ETDEWEB)

    Lyman, J.T.; Ainsworth, E.J.; Alpen, E.L.; Bond, V.; Curtis, S.B.; Fry, R.J.M.; Jackson, K.L.; Nachtwey, S.; Sondhaus, C.; Tobias, C.A.; Fabrikant, J.I.

    1980-11-01

    The radiation risks to the health of workers who will construct and maintain solar power satellites in the space environment were examined. For ionizing radiation, the major concern will be late or delayed health effects, particularly the increased risk of radiation-induced cancer. The estimated lifetime risk for cancer is 0.8 to 5.0 excess deaths per 10,000 workers per rad of exposure. Thus, for example, in 10,000 workers who completed ten missions with an exposure of 40 rem per mission, 320 to 2000 additional deaths in excess of the 1640 deaths from normally occurring cancer, would be expected. These estimates would indicate a 20 to 120% increase in cancer deaths in the worker-population. The wide range in these estimates stems from the choice of the risk-projection model and the dose-response relationsip. The choice between a linear and a linear-quadratic dose-response model may alter the risk estimate by a factor of about two. The method of analysis (e.g., relative vs absolute risk model) can alter the risk estimate by an additional factor of three. Choosing different age and sex distributions can further change the estimate by another factor of up to three. The potential genetic consequences could be of significance, but at the present time, sufficient information on the age and sex distribution of the worker population is lacking for precise estimation of risk. The potential teratogenic consequences resulting from radiation are considered significant. Radiation exposure of a pregnant worker could result in developmental abnormalities.

  19. Experimental Study on the Precise Orbit Determination of the BeiDou Navigation Satellite System

    Directory of Open Access Journals (Sweden)

    Jens Wickert

    2013-03-01

    Full Text Available The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO, five Inclined Geosynchronous Orbit (IGSO satellites and four Medium Earth Orbit (MEO satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better.

  20. Satellite Monitoring Systems for Shipping and Offshore Oil and Gas Industry in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Kostianoy A.G.

    2015-06-01

    Full Text Available Shipping activities, oil production and transport in the sea, oil handled in harbors, construction and exploitation of offshore oil and gas pipelines have a number of negative impacts on the marine environment and coastal zone of the seas. In 2004-2014 we elaborated several operational satellite monitoring systems for oil and gas companies in Russia and performed integrated satellite monitoring of the ecological state of coastal waters in the Baltic, Black, Caspian, and Kara seas, which included observation of oil pollution, suspended matter, and algae bloom at a fully operational mode. These monitoring systems differ from the existing ones by the analysis of a wide spectrum of satellite, meteorological and oceanographic data, as well as by a numerical modeling of oil spill transformation and transport in real weather conditions. Our experience in the Baltic Sea includes: (1 integrated satellite monitoring of oil production at the LUKOIL-KMN Ltd. D-6 oil rig in the Southeastern Baltic Sea (Kravtsovskoe oil field in 2004-2014; (2 integrated satellite monitoring of the “Nord Stream” underwater gas pipeline construction and exploitation in the Gulf of Finland (2010-2013; (3 numerical modeling of risks of oil pollution caused by shipping along the main maritime shipping routes in the Gulf of Finland, the Baltic Proper, and in the Southeastern Baltic Sea; (4 numerical modeling of risks of oil pollution caused by oil production at D-6 oil rig and oil transportation on shore via the connecting underwater oil pipeline.

  1. Direct assimilation of satellite radiance data in GRAPES variational assimilation system

    Institute of Scientific and Technical Information of China (English)

    ZHU GuoFu; XUE JiShan; ZHANG Hua; LIU ZhiQuan; ZHUANG ShiYu; HUANG LiPing; DONG PeiMing

    2008-01-01

    Variational method is capable of dealing with observations that have a complicated nonlinear relation with model variables representative of the atmospheric state, and so make it possible to directly as-similate such measured variables as satellite radiance, which have a nonlinear relation with the model variables. Assimilation of any type of observations requires a corresponding observation operator, which establishes a specific mapping from the space of the model state to the space of observation. This paper presents in detail how the direct assimilation of real satellite radiance data is implemented in the GRAPES-3DVar analysis system. It focuses on all the components of the observation operator for direct assimilation of real satellite radiance data, including a spatial interpolation operator that trans-forms variables from model grid points to observation locations, a physical transformation from model variables to observed elements with different choices of model variables, and a data quality control. Assimilation experiments, using satellite radiances such as NOAA17 AMSU-A and AMSU-B (Advanced Microwave Sounding Unit), are carried out with two different schemes. The results from these experi-ments can be physically understood and clearly reflect a rational effect of direct assimilation of satellite radiance data in GRAPES-3DVar analysis system.

  2. The Multi-Sensor Aerosol Products Sampling System (MAPSS) for Integrated Analysis of Satellite Retrieval Uncertainties

    Science.gov (United States)

    Ichoku, Charles; Petrenko, Maksym; Leptoukh, Gregory

    2010-01-01

    Among the known atmospheric constituents, aerosols represent the greatest uncertainty in climate research. Although satellite-based aerosol retrieval has practically become routine, especially during the last decade, there is often disagreement between similar aerosol parameters retrieved from different sensors, leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. As long as there is no consensus and the inconsistencies are not well characterized and understood ', there will be no way of developing reliable climate data records from satellite aerosol measurements. Fortunately, the most globally representative well-calibrated ground-based aerosol measurements corresponding to the satellite-retrieved products are available from the Aerosol Robotic Network (AERONET). To adequately utilize the advantages offered by this vital resource,., an online Multi-sensor Aerosol Products Sampling System (MAPSS) was recently developed. The aim of MAPSS is to facilitate detailed comparative analysis of satellite aerosol measurements from different sensors (Terra-MODIS, Aqua-MODIS, Terra-MISR, Aura-OMI, Parasol-POLDER, and Calipso-CALIOP) based on the collocation of these data products over AERONET stations. In this presentation, we will describe the strategy of the MAPSS system, its potential advantages for the aerosol community, and the preliminary results of an integrated comparative uncertainty analysis of aerosol products from multiple satellite sensors.

  3. Acceptance Testing of a Satellite SCADA Photovoltaic-Diesel Hybrid System

    Science.gov (United States)

    Kalu, A.; Emrich, C.; Ventre, G.; Wilson, W.; Acosta, Roberto (Technical Monitor)

    2000-01-01

    Satellite Supervisory Control and Data Acquisition (SCADA) of a Photovoltaic (PV)/diesel hybrid system was tested using NASA's Advanced Communication Technology Satellite (ACTS) and Ultra Small Aperture Terminal (USAT) ground stations. The setup consisted of a custom-designed PV/diesel hybrid system, located at the Florida Solar Energy Center (FSEC), which was controlled and monitored at a "remote" hub via Ka-band satellite link connecting two 1/4 Watt USATs in a SCADA arrangement. The robustness of the communications link was tested for remote monitoring of the health and performance of a PV/diesel hybrid system, and for investigating load control and battery charging strategies to maximize battery capacity and lifetime, and minimize loss of critical load probability. Baseline hardware performance test results demonstrated that continuous two-second data transfers can be accomplished under clear sky conditions with an error rate of less than 1%. The delay introduced by the satellite (1/4 sec) was transparent to synchronization of satellite modem as well as to the PV/diesel-hybrid computer. End-to-end communications link recovery times were less than 36 seconds for loss of power and less than one second for loss of link. The system recovered by resuming operation without any manual intervention, which is important since the 4 dB margin is not sufficient to prevent loss of the satellite link during moderate to heavy rain. Hybrid operations during loss of communications link continued seamlessly but real-time monitoring was interrupted. For this sub-tropical region, the estimated amount of time that the signal fade will exceed the 4 dB margin is about 10%. These results suggest that data rates of 4800 bps and a link margin of 4 dB with a 1/4 Watt transmitter are sufficient for end-to-end operation in this SCADA application.

  4. Land Mobile Satellite Service (LMSS): A conceptual system design and identification of the critical technologies: Part 2: Technical report

    Science.gov (United States)

    Naderi, F. (Editor)

    1982-01-01

    A conceptual system design for a satellite-aided land mobile service is described. A geostationary satellite which employs a large (55-m) UHF reflector to communicate with small inexpensive user antennas on mobile vehicles is discussed. It is shown that such a satellite system through multiple beam antennas and frequency reuse can provide thousands of radiotelephone and dispatch channels serving hundreds of thousands of users throughout the U.S.

  5. Global Navigation Satellite System Multipath Mitigation Using a Wave-Absorbing Shield.

    Science.gov (United States)

    Yang, Haiyan; Yang, Xuhai; Sun, Baoqi; Su, Hang

    2016-08-22

    Code multipath is an unmanaged error source in precise global navigation satellite system (GNSS) observation processing that limits GNSS positioning accuracy. A new technique for mitigating multipath by installing a wave-absorbing shield is presented in this paper. The wave-absorbing shield was designed according to a GNSS requirement of received signals and collected measurements to achieve good performance. The wave-absorbing shield was installed at the KUN1 and SHA1 sites of the international GNSS Monitoring and Assessment System (iGMAS). Code and carrier phase measurements of three constellations were collected on the dates of the respective installations plus and minus one week. Experiments were performed in which the multipath of the measurements obtained at different elevations was mitigated to different extents after applying the wave-absorbing shield. The results of an analysis and comparison show that the multipath was mitigated by approximately 17%-36% on all available frequencies of BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), and Global Navigation Satellite System (GLONASS) satellites. The three-dimensional accuracies of BDS, GPS, and GLONASS single-point positioning (SPP) were, respectively, improved by 1.07, 0.63 and 0.49 m for the KUN1 site, and by 0.72, 0.79 and 0.73 m for the SHA1 site. Results indicate that the multipath of the original observations was mitigated by using the wave-absorbing shield.

  6. Effects on biological systems of reflected light from a satellite power system

    Science.gov (United States)

    White, M.

    1981-01-01

    Light reflection produced by the satellite power system and the possible effects of that light on the human eye, plants, and animals were studied. For the human eye, two cases of reflected light, might cause eye damage if viewed for too long. These cases are: (1) if, while in low Earth orbit, the orbital transfer vehicle is misaligned to reflect the Sun to Earth there exists a maximum safe fixation time for the naked eye of 42.4 secs; (2) reflection from the aluminum paint on the back of the orbital transfer vehicle, while in or near low Earth orbit, can be safely viewed by the naked eye for 129 sec. For plants and animals the intensity and timing of light are not a major problem. Ways for reducing and/or eliminating the irradiances are proposed.

  7. Delay analysis of a satellite channel reservation system with variable frame format

    Science.gov (United States)

    Mine, H.; Ohno, K.; Shioyama, T.

    1983-06-01

    In describing the operation, it is pointed out that the current queue length at each user is reported through minislots in the up-link header to a satellite possessing processing capability. The satellite broadcasts slot assignments for transmission in the next frame to users through the down-link header on the basis of the users' reported queue status. The number of data slots per frame varies according to the reported queue status of the users. A Markov-chain model is presented for analyzing the average total delay of the system. Numerical results are given for comparing the delay of the system with the delay of TDMA and reservation systems with fixed frame format. The system is shown to provide a better delay/throughput performance than these other systems over a wide range of traffic intensities. In addition, the delay curve of the system is relatively flat up to a traffic intensity of approximately 0.8.

  8. Satellite constellation design with genetic algorithms based on system performance

    Institute of Scientific and Technical Information of China (English)

    Xueying Wang; Jun Li; Tiebing Wang; Wei An; Weidong Sheng

    2016-01-01

    Satelite constelation design for space optical sys-tems is essentialy a multiple-objective optimization problem. In this work, to tackle this chalenge, we first categorize the performance metrics of the space optical system by taking into account the system tasks (i.e., target detection and tracking). We then propose a new non-dominated sorting genetic algo-rithm (NSGA) to maximize the system surveilance perfor- mance. Pareto optimal sets are employed to deal with the conflicts due to the presence of multiple cost functions. Simulation results verify the validity and the improved per-formance of the proposed technique over benchmark meth-ods.

  9. Development of a Nitrous Oxide-Based Monopropellant Propulsion System for Small Satellites

    OpenAIRE

    Tarantini, Vincent; Risi, Ben; Orr, Nathan

    2016-01-01

    As the demand for highly capable microsatellite missions continues to grow, so too does the need for small yet effective satellite technologies. One area which needs to be addressed is compact propulsion systems capable of performing on-orbit maneuvers, station keeping, and de-orbit impulses with good efficiency. Another important consideration for propulsion systems is the safety and ease in handling, integrating, and testing the propulsion system. This is particularly important for small sa...

  10. Radiation budget and related measurements in 1985 and beyond. [earth radiation budget satellite system

    Science.gov (United States)

    1978-01-01

    Development of systems for obtaining radiation budget and cloud data is discussed. Instruments for measuring total solar irradiance, total infrared flux, reflected solar flux, and cloud heights and properties are considered. Other topics discussed include sampling by multiple satellites, user identification, and determination of the parameters that need to be measured.

  11. The method of the antenna system positioning for satellite communication network radiomonitoring complex

    OpenAIRE

    Гребенюк, Олег Петрович

    2014-01-01

    The method of orientation of the antenna system of complex of radiomonitoring of satellite communication networks is offered. A method takes into account the features of construction and functional setting of a transport stream of standard of DVB ‑ S.

  12. MISAT : Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully

  13. Study on networking issues of medium earth orbit satellite communications systems

    Science.gov (United States)

    Araki, Noriyuki; Shinonaga, Hideyuki; Ito, Yasuhiko

    1993-01-01

    Two networking issues of communications systems with medium earth orbit (MEO) satellites, namely network architectures and location determination and registration methods for hand-held terminals, are investigated in this paper. For network architecture, five candidate architectures are considered and evaluated in terms of signaling traffic. For location determination and registration, two methods are discussed and evaluated.

  14. Modeling radiation conditions in orbits of projected system of small satellites for radiation monitoring

    Science.gov (United States)

    Panasyuk, M. I.; Podzolko, M. V.; Kovtyukh, A. S.; Osedlo, V. I.; Tulupov, V. I.; Yashin, I. V.

    2016-11-01

    Calculated estimates are presented for the accumulated radiation doses behind the shields of various thicknesses in the orbits of projected at Skobeltsyn Institute of Nuclear Physics, Moscow State University system of small satellites for radiation monitoring. The results are analyzed and compared with the calculation data for other actively exploited near-Earth orbits.

  15. Discovery of a New AM CVn System with the Kepler Satellite

    DEFF Research Database (Denmark)

    Fontaine, G.; Brassard, P.; Green, Elizabeth M.;

    2011-01-01

    We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler target lists as a potential compact pulsator, the blue object SDSS J190817.07+394036.4 (KIC...

  16. MISAT : Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully ex

  17. Next-generation satellite gravimetry for measuring mass transport in the Earth system

    NARCIS (Netherlands)

    Teixeira Encarnação, J.

    2015-01-01

    The main objective of the thesis is to identify the optimal set-up for future satellite gravimetry missions aimed at monitoring mass transport in the Earth’s system.The recent variability of climatic patterns, the spread of arid regions and associ- ated changes in the hydrological cycle, and vigorou

  18. Error analysis for relay type satellite-aided search and rescue systems

    Science.gov (United States)

    Marini, J. W.

    1979-01-01

    An analysis is made of the errors in the determination of the position of an emergency transmitter in a satellite-aided search and rescue system. The satellite is assumed to be at a height of 820 km in a near-circular near polar orbit. Short data spans of four minutes or less are used. The error sources considered are measurement noise, transmitter frequency drift, ionospheric effects, and error in the assumed height of the transmitter. The errors are calculated for several different transmitter positions, data rates, and data spans. The only transmitter frequency used was 406 MHz, but the result can be scaled to different frequencies.

  19. Innovative use of global navigation satellite systems for flight inspection

    Science.gov (United States)

    Kim, Eui-Ho

    The International Civil Aviation Organization (ICAO) mandates flight inspection in every country to provide safety during flight operations. Among many criteria of flight inspection, airborne inspection of Instrument Landing Systems (ILS) is very important because the ILS is the primary landing guidance system worldwide. During flight inspection of the ILS, accuracy in ILS landing guidance is checked by using a Flight Inspection System (FIS). Therefore, a flight inspection system must have high accuracy in its positioning capability to detect any deviation so that accurate guidance of the ILS can be maintained. Currently, there are two Automated Flight Inspection Systems (AFIS). One is called Inertial-based AFIS, and the other one is called Differential GPS-based (DGPS-based) AFIS. The Inertial-based AFIS enables efficient flight inspection procedures, but its drawback is high cost because it requires a navigation-grade Inertial Navigation System (INS). On the other hand, the DGPS-based AFIS has relatively low cost, but flight inspection procedures require landing and setting up a reference receiver. Most countries use either one of the systems based on their own preferences. There are around 1200 ILS in the U.S., and each ILS must be inspected every 6 to 9 months. Therefore, it is important to manage the airborne inspection of the ILS in a very efficient manner. For this reason, the Federal Aviation Administration (FAA) mainly uses the Inertial-based AFIS, which has better efficiency than the DGPS-based AFIS in spite of its high cost. Obviously, the FAA spends tremendous resources on flight inspection. This thesis investigates the value of GPS and the FAA's augmentation to GPS for civil aviation called the Wide Area Augmentation System (or WAAS) for flight inspection. Because standard GPS or WAAS position outputs cannot meet the required accuracy for flight inspection, in this thesis, various algorithms are developed to improve the positioning ability of Flight

  20. Evaluating the Cloud Cover Forecast of NCEP Global Forecast System with Satellite Observation

    CERN Document Server

    Ye, Quanzhi

    2011-01-01

    To assess the quality of daily cloud cover forecast generated by the operational global numeric model, the NCEP Global Forecast System (GFS), we compose a large sample with outputs from GFS model and satellite observations from the International Satellite Cloud Climatology Project (ISCCP) in the period of July 2004 to June 2008, to conduct a quantitative and systematic assessment of the performance of a cloud model that covers a relatively long range of time, basic cloud types, and in a global view. The evaluation has revealed the goodness of the model forecast, which further illustrates our completeness on understanding cloud generation mechanism. To quantity the result, we found a remarkably high correlation between the model forecasts and the satellite observations over the entire globe, with mean forecast error less than 15% in most areas. Considering a forecast within 30% difference to the observation to be a "good" one, we find that the probability for the GFS model to make good forecasts varies between...

  1. Telecommunication service markets through the year 2000 in relation to millimeter wave satellite systems

    Science.gov (United States)

    Stevenson, S. M.

    1979-01-01

    NASA is currently conducting a series of millimeter wave satellite system and market studies to develop 30/20 GHz satellite system concepts that have commercial potential for the period 1980-2000. The results of the market studies to-date focusing on the overall demand forecasts and distributions by geographic location, distance, and user category are discussed. Tables are presented indicating baseline market forecast voice and video services, data service category, impacted baseline forecast, and traffic/distance distribution voice services. It is concluded that the total market and system activity will be influential in determining the potential role of millimeter wave systems in the overall transmission needs of the nation, and the amount of the total forecasted traffic suitable for millimeter wave systems.

  2. Networks systems and operations. [wideband communication techniques for data links with satellites

    Science.gov (United States)

    1975-01-01

    The application of wideband communication techniques for data links with satellites is discussed. A diagram of the demand assigned voice communications system is provided. The development of prototype integrated spacecraft paramps at S- and C-bands is described and the performance of space-qualified paramps is tabulated. The characteristics of a dual parabolic cylinder monopulse zoom antenna for use with the tracking and data relay satellite system (TDRSS) are analyzed. The development of a universally applicable transponder at S-band is reported. A block diagram of the major subassemblies of the S-band transponder is included. The technology aspects of network timing and synchronization of communication systems are to show the use of the Omega navigation system. The telemetry data compression system used during the Skylab program is evaluated.

  3. The Design and Implementation of a Remote Fault Reasoning Diagnosis System for Meteorological Satellites Data Acquisition

    Directory of Open Access Journals (Sweden)

    Zhu Jie

    2017-01-01

    Full Text Available Under the background of the trouble shooting requirements of FENGYUN-3 (FY-3 meteorological satellites data acquisition in domestic and oversea ground stations, a remote fault reasoning diagnosis system is developed by Java 1.6 in eclipse 3.6 platform. The general framework is analyzed, the workflow is introduced. Based on the system, it can realize the remote and centralized monitoring of equipment running status in ground stations,triggering automatic fault diagnosis and rule based fault reasoning by parsing the equipment quality logs, generating trouble tickets and importing expert experience database, providing text and graphics query methods. Through the practical verification, the system can assist knowledge engineers in remote precise and rapid fault location with friendly graphical user interface, boost the fault diagnosis efficiency, enhance the remote monitoring ability of integrity operating control system. The system has a certain practical significance to improve reliability of FY-3 meteorological satellites data acquisition.

  4. Grand Challenges in Space Technology: Distributed Satellite Systems

    Science.gov (United States)

    2001-07-01

    modem interests in readability, extensibility and expressiveness. To achieve these goals Embedded C ++ (EC++) has been chosen as the standard for GRRDE...of embedded C ++ as a programming language for FSW. The ongoing simulation of the TechSat21 system will provide an invaluable analysis of this mission...time. The study has also demonstrated the suitability of OSE as a real-time distributed operating system and of embedded C ++ as a programming language

  5. 78 FR 21629 - Certain Two-Way Global Satellite Communication Devices, System and Components Thereof Issuance of...

    Science.gov (United States)

    2013-04-11

    ... COMMISSION Certain Two-Way Global Satellite Communication Devices, System and Components Thereof Issuance of... importation, and the sale within the United States after importation of certain two-way global satellite communication devices, system and components thereof by reason of infringement of certain claims of U.S. Patent...

  6. Wildland fire management. Volume 2: Wildland fire control 1985-1995. [satellite information system for California fire problems

    Science.gov (United States)

    Saveker, D. R. (Editor)

    1973-01-01

    The preliminary design of a satellite plus computer earth resources information system is proposed for potential uses in fire prevention and control in the wildland fire community. Suggested are satellite characteristics, sensor characteristics, discrimination algorithms, data communication techniques, data processing requirements, display characteristics, and costs in achieving the integrated wildland fire information system.

  7. Satellite laser ranging measurements in South Africa: Contributions to earth system sciences

    Directory of Open Access Journals (Sweden)

    Christina M. Botai

    2015-03-01

    Full Text Available This contribution reassesses progress in the development of satellite laser ranging (SLR technology and its scientific and societal applications in South Africa. We first highlight the current global SLR tracking stations within the framework of the International Laser Ranging Service (ILRS and the artificial satellites currently being tracked by these stations. In particular, the present work focuses on analysing SLR measurements at Hartebeesthoek Radio Astronomy Observatory (HartRAO, South Africa, based on the MOBLAS-6 SLR configuration. Generally, there is a weak geometry of ILRS stations in the southern hemisphere and the SLR tracking station at HartRAO is the only active ILRS station operating on the African continent. The SLR-derived products such as station positions and velocities, satellite orbits, components of earth's gravity field and their temporal variations, earth orientation parameters are collected, merged, achieved and distributed by the ILRS under the Crustal Dynamic Data Information System. These products are used in various research fields such as detection and monitoring of tectonic plate motion, crustal deformation, earth rotation, polar motion, and the establishment and monitoring of International Terrestrial Reference Frames, as well as modelling of the spatio-temporal variations of the earth's gravity field. The MOBLAS-6 tracking station is collocated with other geodetic techniques such as very long baseline interferometry and Global Navigation Satellite Systems, thus making this observatory a fiducial geodetic location. Some applications of the SLR data products are described within the context of earth system science.

  8. Environmental assessment for the satellite power system concept development and evaluation program: atmospheric effects

    Energy Technology Data Exchange (ETDEWEB)

    Rote, D.M.; Brubaker, K.L.; Lee, J.L.

    1980-11-01

    The US Department of Energy (DOE) has undertaken a preliminary, three-year program to investigate the impacts of the construction and operation of a satellite power system, of unprecedented scale. The Department of Energy's program, titled The Concept Development and Evaluation Program, focused its investigations on a Reference System description that calls for the use of either silicon (Si) or gallium aluminum-arsenide (GaAlAs) photovoltaic cells on 60 satellites to be constructed in GEO over a 30-yr period. Rectennas would be constructed on the ground to receive microwave energy from the satellites. Each satellite-rectenna pair is designed to produce 5 GW of power on an essentially continuous basis for use as a baseload power source for an electric power distribution system. The environmental assessment part of the program was divided into five interdependent task areas. The present document constitutes the final technical report on one of the five task areas, the Assessment of the Atmospheric Effects, and as such presents an in-depth summary of work performed during the assessment program. The issues associated with SPS activities in the troposphere are examined. These include tropospheric weather modification related to rectenna operations and rocket launches, and air quality impacts related to rocketlaunch ground clouds. Then progressing upward through the various levels of the atmosphere, the principal middle and upper atmospheric effects associated with rocket effluents are analyzed. Finally, all of the potential SPS atmospheric effects are summarized.

  9. Low-Power Reflective Optical Communication System for Pico- and Nano-Satellites

    Science.gov (United States)

    Sinn, A.; Riel, T.; Deisl, F.; Saathof, R.; Schitter, G.

    2016-09-01

    Pico- and nano-satellites (PNS) are promising options for cost-effective and rapid deployable satellite systems. Due to their small size, the available power and therefore the transmittable data volume is limited. This paper proposes optical communication by means of reflected laser light using a modulating retro-reflector (MRR) for energy efficient optical communication with PNS. No laser source or beam steering assembly is necessary at the satellite, thus allowing a weight and energy efficient communication interface. Existing ground stations (GS) as used for satellite laser ranging (SLR) provide all equipment required for this system. By providing a link budget for communication to PNS in LEOs feasibility is investigated. It is shown that an affordable GS based on small telescopes with diameters below 0.3m in combination with commercial mounts enables the targeted application. A detailed analysis of LCD based MRRs is shown, denoting cost-efficient modulators for reflective optical communication. A data-rate of 2.5kbps at an input power of less than 80 mW is shown in a laboratory setup. Using a high performance sampling circuit and a laser power of only 1mW, a bit error ratio (BER) of below 10e-3 is achieved, successfully demonstrating reflective optical communication as an alternative to current RF based systems.

  10. Potential markets for a satellite-based mobile communications system

    Science.gov (United States)

    Jamieson, W. M.; Peet, C. S.; Bengston, R. J.

    1976-01-01

    The objective of the study was to define the market needs for improved land mobile communications systems. Within the context of this objective, the following goals were set: (1) characterize the present mobile communications industry; (2) determine the market for an improved system for mobile communications; and (3) define the system requirements as seen from the potential customer's viewpoint. The scope of the study was defined by the following parameters: (1) markets were confined to U.S. and Canada; (2) range of operation generally exceeded 20 miles, but this was not restrictive; (3) the classes of potential users considered included all private sector users, and non-military public sector users; (4) the time span examined was 1975 to 1985; and (5) highly localized users were generally excluded - e.g., taxicabs, and local paging.

  11. Augmented tracking and acquisition system for GBL satellite illumination

    Science.gov (United States)

    Brodsky, Aaron; Goodrich, Alan; Lawson, David G.; Holm, Richard W.

    1991-08-01

    The Augmented Tracking and Acquisition System (ATAS) provides the tracking acquisition aids, line-of-sight stabilization, and active closed-loop beam centering functions at two ground-based laser tracking sites for the Relay Mirror Experiment (RME). Simultaneous, steady illumination of the RME spacecraft with both ground beacons allows for successful beam relay between the two sites off of the orbiting mirror. Described in this paper is an overview of the functions, control system architectures, major subsystem components (steering mirrors and sensors), and mission operation of the ATAS subsystems. A brief discussion of ATAS evolution is included to show that versatility is needed for success.

  12. Iodine Propulsion Advantages for Low Cost Mission Applications and the Iodine Satellite (ISAT) Technology Demonstration

    Science.gov (United States)

    Dankanich, John W.; Schumacher, Daniel M.

    2015-01-01

    The NASA Marshall Space Flight Center Science and Technology Office is continuously exploring technology options to increase performance or reduce cost and risk to future NASA missions including science and exploration. Electric propulsion is a prevalent technology known to reduce mission costs by reduction in launch costs and spacecraft mass through increased post launch propulsion performance. The exploration of alternative propellants for electric propulsion continues to be of interest to the community. Iodine testing has demonstrated comparable performance to xenon. However, iodine has a higher storage density resulting in higher ?V capability for volume constrained systems. Iodine's unique properties also allow for unpressurized storage yet sublimation with minimal power requirements to produce required gas flow rates. These characteristics make iodine an ideal propellant for secondary spacecraft. A range of mission have been evaluated with a focus on low-cost applications. Results highlight the potential for significant cost reduction over state of the art. Based on the potential, NASA has been developing the iodine Satellite for a near-term iodine Hall propulsion technology demonstration. Mission applications and progress of the iodine Satellite project are presented.

  13. Design, Fabrication and Testing of a Satellite Electron Beam System.

    Science.gov (United States)

    1980-05-16

    SEBS passed the requirement of a remanent magnetic field at a distance of one meter no more than 4xlO -4 gauss . The SPIBS system utilized a permanent...to 32 volts for test purposes. The upper right hand side of the panel contains a 50 pin Cannon D connector to carry the command signals to the SPIBS

  14. Modular Thruster and Feeding System for Micro-Satellite

    NARCIS (Netherlands)

    Louwerse, M.C.; Jansen, Henricus V.; Elwenspoek, Michael Curt

    2008-01-01

    The miniaturization of space applicable devices by means of micro system technology (MST) is pursued by many research groups. MST devices are often designed as stand alone and require individual packaging which makes them still quite large. Focusing on the integration of several MST components has

  15. PERFORMANCE ANALYSIS AND SIMULATION OF VARIOUS BURST TIME PLAN GENERATION METHODS IN BROADBAND SATELLITE MULTIMEDIA SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Feng Shaodong; Li Guangxia; Feng Qi

    2011-01-01

    The Burst Time Plan (BTP) generation is the key for resource allocation in Broadband Satellite Multimedia (BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused by BTP generation as well as maintain the Quality of Service (QoS) and improve the channel utilization efficiency.Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm.Based on the analysis we find that Periodical BTP Generation (P-BTPG) method cannot guarantee the delay performance,channel utilization efficiency and QoS simultaneously,especially when the capacity requests arrived randomly.The Optimized BTP Generation (O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead.Finally,a novel Asynchronous BTP Generation (A-BTPG) method is proposed which is invoked according to users' requests.A BSM system application scenario is simulated.Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern.This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite (DVB-RCS) system or IP onboard routing BSM system in the future.

  16. Optimization and Feasibility Analysis of Satellite Earth Station Power System Using Homer

    Directory of Open Access Journals (Sweden)

    Hassen T. Dorrah

    2012-06-01

    Full Text Available Satellite earth stations which located in remote areas are one of many applications powered by the renewable energy sources. Ground system consists of ground station and control centers working together to support the spacecraft and the data user. Earth station consists of major subsystems, transmitter, receiver, antenna, tracking equipment, terrestrial interface equipment and power supply. Power subsystem is an important part that required for supplying the earth station with electrical power to continue communicating with its remote sensing satellite. This paper deals with simulation and optimal sizing of earth station power system using HOMER software. A combination of two energy sources (solar, and wind to provide a continuous electric power production is used to determine the optimum system operation. Three system configurations are compared with respect to the total net present cost (NPC and levelized cost of energy (COE. Also, economical study will be analyzed for energy demand and sensitivity analysis will be performed.

  17. Performance analysis of MRC spatial diversity receiver system for satellite-to-ground downlink optical transmissions

    Science.gov (United States)

    Li, Kangning; Ma, Jing; Tan, Liying; Yu, Siyuan; Cao, Yubin

    2016-10-01

    The performances of satellite-to-ground downlink optical communications over Gamma-Gamma distributed turbulence are studied for multiple apertures receiver system. Maximum ratio combining (MRC) technique is considered as a combining scheme to mitigate the atmospheric turbulence under thermal noise limited conditions. Bit-error rate (BER) performances for on-off keying (OOK) modulated direct detection optical communications are analyzed for MRC diversity receptions through an approximation method. To show the net diversity gain of multiple apertures receiver system, BER performances of MRC receiver system are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power) for satellite-to-ground downlink optical communications. All the numerical results are also verified by Monte-Carlo (MC) simulations.

  18. Optimization and Feasibility Analysis of Satellite Earth Station Power System Using Homer

    Directory of Open Access Journals (Sweden)

    Hassen T. Dorrah

    2012-06-01

    Full Text Available Satellite earth stations which located in remote areas are one of many applications powered by the renewable energy sources. Ground system consists of ground station and control centers working together to support the spacecraft and the data user. Earth station consists of major subsystems, transmitter, receiver, antenna, tracking equipment, terrestrial interface equipment and power supply. Power subsystem is an important part that required for supplying the earth station with electrical power to continue communicating with its remote sensing satellite. This paper deals with simulation and optimal sizing of earth station power system using HOMER software. A combination of two energy sources (solar, and wind to provide a continuous electric power production is used to determine the optimum system operation. Three system configurations are compared with respect to the total net present cost (NPC and levelized cost of energy (COE. Also, economical study will be analyzed for energy demand and sensitivity analysis will be performed.

  19. Numerical simulations of the electrodynamic interactions between the Tethered-Satellite-System and space plasma

    Science.gov (United States)

    Vashi, Bharat I.

    1992-01-01

    The first Tethered-Satellite-System (TSS-1), scheduled for a flight in late 1992, is expected to provide relevant information related to the concept of generating an emf in a 20-km-long (or longer) conducting wire. This paper presents numerical simulations of the electrodynamic interactions between the TSS system and space plasma, using a 2D and 3D models of the system. The 2D case code simulates the motion of a long cylinder past a plasma, which is composed of electrons and H(+) ions. The system is solved by allowing the plasma to flow past the cylinder with an imposed magnetic field. The more complex 3D case is considered to study the dynamics in great detail. Results of 2D simulation show that the interaction of a satellite with plasma flowing perpendicularly to the magnetic field results in an enhancement in the current collection.

  20. A gradual neural-network approach for frequency assignment in satellite communication systems.

    Science.gov (United States)

    Funabiki, N; Nishikawa, S

    1997-01-01

    A novel neural-network approach called gradual neural network (GNN) is presented for a class of combinatorial optimization problems of requiring the constraint satisfaction and the goal function optimization simultaneously. The frequency assignment problem in the satellite communication system is efficiently solved by GNN as the typical problem of this class. The goal of this NP-complete problem is to minimize the cochannel interference between satellite communication systems by rearranging the frequency assignment so that they can accommodate the increasing demands. The GNN consists of NxM binary neurons for the N-carrier-M-segment system with the gradual expansion scheme of activated neurons. The binary neural network achieves the constrain satisfaction with the help of heuristic methods, whereas the gradual expansion scheme seeks the cost optimization. The capability of GNN is demonstrated through solving 15 instances in practical size systems, where GNN can find far better solutions than the existing algorithm.

  1. Building high-performance system for processing a daily large volume of Chinese satellites imagery

    Science.gov (United States)

    Deng, Huawu; Huang, Shicun; Wang, Qi; Pan, Zhiqiang; Xin, Yubin

    2014-10-01

    The number of Earth observation satellites from China increases dramatically recently and those satellites are acquiring a large volume of imagery daily. As the main portal of image processing and distribution from those Chinese satellites, the China Centre for Resources Satellite Data and Application (CRESDA) has been working with PCI Geomatics during the last three years to solve two issues in this regard: processing the large volume of data (about 1,500 scenes or 1 TB per day) in a timely manner and generating geometrically accurate orthorectified products. After three-year research and development, a high performance system has been built and successfully delivered. The high performance system has a service oriented architecture and can be deployed to a cluster of computers that may be configured with high end computing power. The high performance is gained through, first, making image processing algorithms into parallel computing by using high performance graphic processing unit (GPU) cards and multiple cores from multiple CPUs, and, second, distributing processing tasks to a cluster of computing nodes. While achieving up to thirty (and even more) times faster in performance compared with the traditional practice, a particular methodology was developed to improve the geometric accuracy of images acquired from Chinese satellites (including HJ-1 A/B, ZY-1-02C, ZY-3, GF-1, etc.). The methodology consists of fully automatic collection of dense ground control points (GCP) from various resources and then application of those points to improve the photogrammetric model of the images. The delivered system is up running at CRESDA for pre-operational production and has been and is generating good return on investment by eliminating a great amount of manual labor and increasing more than ten times of data throughput daily with fewer operators. Future work, such as development of more performance-optimized algorithms, robust image matching methods and application

  2. Magnetic Field Satellite (Magsat) data processing system specifications

    Science.gov (United States)

    Berman, D.; Gomez, R.; Miller, A.

    1980-01-01

    The software specifications for the MAGSAT data processing system (MDPS) are presented. The MDPS is divided functionally into preprocessing of primary input data, data management, chronicle processing, and postprocessing. Data organization and validity, and checks of spacecraft and instrumentation are dicussed. Output products of the MDPS, including various plots and data tapes, are described. Formats for important tapes are presented. Dicussions and mathematical formulations for coordinate transformations and field model coefficients are included.

  3. Phased Antenna Array for Global Navigation Satellite System Signals

    Science.gov (United States)

    Turbiner, Dmitry (Inventor)

    2015-01-01

    Systems and methods for phased array antennas are described. Supports for phased array antennas can be constructed by 3D printing. The array elements and combiner network can be constructed by conducting wire. Different parameters of the antenna, like the gain and directivity, can be controlled by selection of the appropriate design, and by electrical steering. Phased array antennas may be used for radio occultation measurements.

  4. Satellite power systems (SPS) concept definition study. Volume 7: SPS program plan and economic analysis, appendixes

    Science.gov (United States)

    Hanley, G.

    1978-01-01

    Three appendixes in support of Volume 7 are contained in this document. The three appendixes are: (1) Satellite Power System Work Breakdown Structure Dictionary; (2) SPS cost Estimating Relationships; and (3) Financial and Operational Concept. Other volumes of the final report that provide additional detail are: Executive Summary; SPS Systems Requirements; SPS Concept Evolution; SPS Point Design Definition; Transportation and Operations Analysis; and SPS Technology Requirements and Verification.

  5. Performance Measurements of the Submillimeter Wave Astronomy Satellite (SWAS) Solar Array Deployment System

    OpenAIRE

    Sneiderman, Gary

    1995-01-01

    This paper discusses some unique features of the solar array deployment system used on the Submillimeter Wave Astronomy Satellite (SWAS). The mechanism system is highly optimized, incorporates no single-use components, and is fully testable in a one-"g" environment. A single High Output Paraffin (HOP) linear actuator drives the mechanisms used to deploy and lock each wing of solar array panels. The solar arrays open slowly, requiring only enough force to overcome inefficiencies and friction. ...

  6. Long-term evolution of the inclined geosynchronous orbit in Beidou Navigation Satellite System

    Science.gov (United States)

    Tang, Jingshi; Hou, Xiyun; Liu, Lin

    2016-07-01

    China's Beidou Navigation Satellite System (BDS), unlike other navigation satellite systems, uses several inclined geosynchronous orbits (IGSO) to enhance the accuracy of regional or global navigation. In order to maintain a safe space environment in the vicinity of its operational orbit, it is necessary that the decommissioned satellites be well disposed of. Following up the study on the specific BDS IGSO satellites in the previous COSPAR Scientific Assembly, we now extend the study to understand the underlying dynamics and discuss the long-term evolution of such orbits from a more general perspective. In this paper, we first theoretically analyze the problem using simplified models of 1 and 2 degrees of freedoms (1-/2-dof). Then we extensively investigate the numerically propagated orbits for 200 and 1000 years, applying the results from these simplified models and seeking proper explanations for the underlying dynamics. We especially focus on the eccentricity evolution, which is a major concern regarding the collision hazard. We expect to understand the underlying dynamics governing the long-term evolution of BDS IGSO and gain helpful insight into future disposal strategies.

  7. Satellite-based assessment of yield variation and its determinants in smallholder African systems

    Science.gov (United States)

    Lobell, David B.

    2017-01-01

    The emergence of satellite sensors that can routinely observe millions of individual smallholder farms raises possibilities for monitoring and understanding agricultural productivity in many regions of the world. Here we demonstrate the potential to track smallholder maize yield variation in western Kenya, using a combination of 1-m Terra Bella imagery and intensive field sampling on thousands of fields over 2 y. We find that agreement between satellite-based and traditional field survey-based yield estimates depends significantly on the quality of the field-based measures, with agreement highest (R2 up to 0.4) when using precise field measures of plot area and when using larger fields for which rounding errors are smaller. We further show that satellite-based measures are able to detect positive yield responses to fertilizer and hybrid seed inputs and that the inferred responses are statistically indistinguishable from estimates based on survey-based yields. These results suggest that high-resolution satellite imagery can be used to make predictions of smallholder agricultural productivity that are roughly as accurate as the survey-based measures traditionally used in research and policy applications, and they indicate a substantial near-term potential to quickly generate useful datasets on productivity in smallholder systems, even with minimal or no field training data. Such datasets could rapidly accelerate learning about which interventions in smallholder systems have the most positive impact, thus enabling more rapid transformation of rural livelihoods. PMID:28202728

  8. Effectiveness of adaptive optics system in satellite-to-ground coherent optical communication.

    Science.gov (United States)

    Jian, Huang; Ke, Deng; Chao, Liu; Peng, Zhang; Dagang, Jiang; Zhoushi, Yao

    2014-06-30

    Adaptive optics (AO) systems can suppress the signal fade induced by atmospheric turbulence in satellite-to-ground coherent optical communication. The lower bound of the signal fade under AO compensation was investigated by analyzing the pattern of aberration modes for a one-stage imaging AO system. The distribution of the root mean square of the residual aberration is discussed on the basis of the spatial and temporal characteristics of the residual aberration of the AO system. The effectiveness of the AO system for improving the performance of coherent optical communication is presented in terms of the bit error rate and system availability.

  9. Multi-antenna synchronized global navigation satellite system receiver and its advantages in high-precision positioning applications

    Science.gov (United States)

    Dong, Danan; Chen, Wen; Cai, Miaomiao; Zhou, Feng; Wang, Minghua; Yu, Chao; Zheng, Zhengqi; Wang, Yuanfei

    2016-12-01

    The multi-antenna synchronized global navigation satellite system receiver is a high precision, low cost, and widely used emerging receiver. Using this type of receiver, the satellite and receiver clock errors can be eliminated simultaneously by forming between antenna single-differences, which is equivalent to the conventional double-difference model. However, current multi-antenna synchronized global navigation satellite system receiver products have not fully realized their potential to achieve better accuracy, efficiency, and broader applications. This paper introduces the conceptual design and derivable products of multi-antenna synchronized global navigation satellite system receivers involving the aspects of attitude determination, multipath effect mitigation, phase center variation correction, and ground-based carrier phase windup calibration. Through case studies, the advantages of multi-antenna synchronized global navigation satellite system receivers in high-precision positioning applications are demonstrated.

  10. Monitoring volcanic systems through cross-correlation of coincident A-Train satellite data.

    Science.gov (United States)

    Flower, V. J. B.; Carn, S. A.; Wright, R.

    2014-12-01

    The remote location and inaccessibility of many active volcanic systems around the world hinders detailed investigation of their eruptive dynamics. One methodology for monitoring such locations is through the utilisation of multiple satellite datasets to elucidate underlying eruption dynamics and aid volcanic hazard mitigation. Whilst satellite datasets are often analysed individually, here we exploit the multi-platform NASA A-Train satellite constellation, including the Ozone Monitoring Instrument (OMI) on Aura and Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua. OMI measures volcanic emissions (e.g. sulphur dioxide, ash) whilst MODIS enables monitoring of thermal anomalies (e.g. lava flows, lava lakes, pyroclastic deposits), allowing analysis of a more diverse range of volcanic unrest than is possible using a single measurement technique alone, and permitting cross-correlation between datasets for specific locations to assess cyclic activity. A Multi-taper (MTM) Fast Fourier Transform (FFT) analysis was implemented at an initial sample site (Soufriere Hills volcano [SHV], Montserrat) facilitating cycle identification and subsequent comparison with existing ground-based data. Corresponding cycles at intervals of 8, 12 and ~50 days were identified in both the satellite-based SO2 and thermal infrared signals and ground-based SO2 measurements (Nicholson et al. 2013), validating the methodology. Our analysis confirms the potential for identification of cyclical volcanic activity through synergistic analysis of satellite data, which would be of particular value at poorly monitored volcanic systems. Following our initial test at SHV, further sample sites have been selected in locations with varied eruption dynamics and monitoring capabilities including Ambrym (Vanuatu), Kilauea (Hawaii), Nyiragongo (DR Congo) and Etna (Italy) with the intention of identifying not only cyclic signals that can be attributed to volcanic systems but also those which are

  11. Deep Charging Evaluation of Satellite Power and Communication System Components

    Science.gov (United States)

    Schneider, T. A.; Vaughn, J. A.; Chu, B.; Wong, F.; Gardiner, G.; Wright, K. H.; Phillips, B.

    2016-01-01

    A set of deep charging tests has been carried out by NASA's Marshall Space Flight Center on subscale flight-like samples developed by Space Systems/Loral, LLC. The samples, which included solar array wire coupons, a photovoltaic cell coupon, and a coaxial microwave transmission cable, were placed in passive and active (powered) circuit configurations and exposed to electron radiation. The energy of the electron radiation was chosen to deeply penetrate insulating (dielectric) materials on each sample. Each circuit configuration was monitored to determine if potentially damaging electrostatic discharge events (arcs) were developed on the coupon as a result of deep charging. The motivation for the test, along with charging levels, experimental setup, sample details, and results will be discussed.

  12. Development of a web-based picture archiving and communication system using satellite data communication.

    Science.gov (United States)

    Hwang, S; Lee, J; Kim, H; Lee, M

    2000-01-01

    Using the JAVA language we have developed a Web-based picture archiving and communication system (PACS) which allows a remote hospital to access medical images. An asymmetric satellite data communication system (ASDCS) provided a receive-only link for data delivery and a conventional terrestrial link (which could be the conventional telephone network) allowed data transmission. The satellite communication link was 10-30 times faster than the conventional terrestrial link. To increase image transmission speeds over the Internet connection, JPEG and wavelet compression methods were used. The resulting images were evaluated quantitatively by measuring the peak signal:noise ratio and qualitatively by radiologists. Compression ratios of 10:1 or less were deemed acceptable for diagnostic purposes. The system appears to be suitable for teleradiology and telemedicine.

  13. Alkaline regenerative fuel cell energy storage system for manned orbital satellites

    Science.gov (United States)

    Martin, R. E.; Gitlow, B.; Sheibley, D. W.

    1982-01-01

    It is pointed out that the alkaline regenerative fuel cell system represents a highly efficient, lightweight, reliable approach for providing energy storage in an orbiting satellite. In addition to its energy storage function, the system can supply hydrogen and oxygen for attitude control of the satellite and for life support. A summary is presented of the results to date obtained in connection with the NASA-sponsored fuel cell technology advancement program, giving particular attention to the requirements of the alkaline regenerative fuel cell and the low-earth mission. Attention is given to system design guidelines, weight considerations, gold-platinum cathode cell performance, matrix development, the electrolyte reservoir plate, and the cyclical load profile tests.

  14. A Comparison Of A Solar Power Satellite Concept To A Concentrating Solar Power System

    Science.gov (United States)

    Smitherman, David V.

    2013-01-01

    A comparison is made of a Solar Power Satellite concept in geostationary Earth orbit to a Concentrating Solar Power system on the ground to analyze overall efficiencies of each infrastructure from solar radiance at 1 AU to conversion and transmission of electrical energy into the power grid on the Earth's surface. Each system is sized for a 1-gigawatt output to the power grid and then further analyzed to determine primary collector infrastructure areas. Findings indicate that even though the Solar Power Satellite concept has a higher end-to-end efficiency, that the combined space and ground collector infrastructure is still about the same size as a comparable Concentrating Solar Power system on the ground.

  15. Experimental verification of chaotic control of an underactuated tethered satellite system

    Science.gov (United States)

    Pang, Zhaojun; Jin, Dongping

    2016-03-01

    This paper studies chaotic control of a tethered satellite system (TSS) driven only by a momentum-exchange device during its attitude adjustment. In dealing with such the underactuated system, an extended time-delay autosynchronization (ETDAS) is employed to stabilize the chaotic motion to a periodic motion. To obtain the control domains of the ETDAS method, a stability analysis of the controlled tethered satellite system in elliptical orbit is implemented. According to the principle of dynamic similarity, then, ground-based experiment setups are proposed and designed to emulate the in-plane motions of the TSS. Representative experiments are presented to demonstrate the effectiveness of the ETDAS scheme in controlling the chaotic motion of the underactuated TSS.

  16. 区域卫星导航系统的卫星星座%Satellite Constellation of Local Navigation System

    Institute of Scientific and Technical Information of China (English)

    许其凤

    2001-01-01

    The orbit of the satellite constellation for local navigation system is discussed. The accuracy of satellite orbit determination and economics of satellite usage is compared for diffenent kinds of satellite.%讨论了区域卫星导航系统卫星星座设计中所用卫星轨道类型。重点讨论了卫星定轨精度、卫星利用率等问题,比较了它们在区域卫星导航系统中的适用性。

  17. Use of negotiated rulemaking in developing technical rules for low-Earth orbit mobile satellite systems

    Science.gov (United States)

    Taylor, Leslie A.

    Technical innovations have converged with the exploding market demand for mobile telecommunications to create the impetus for low-earth orbit (LEO) communications satellite systems. The so-called 'Little LEO's' propose use of VHF and UHF spectrum to provide position - location and data messaging services. The so-called 'Big LEO's' propose to utilize the RDSS bands to provide voice and data services. In the United States, several applications were filed with the U.S. Federal Communications Commission (FCC) to construct and operate these mobile satellite systems. To enable the prompt introduction of such new technology services, the FCC is using innovative approaches to process the applications. Traditionally, when the FCC is faced with 'mutually exclusive' applications, e.g. a grant of one would preclude a grant of the others, it uses selection mechanisms such as comparative hearings or lotteries. In the case of the LEO systems, the FCC has sought to avoid these time-consuming approaches by using negotiated rulemakings. The FCC's objective is to enable the multiple applicants and other interested parties to agree on technical and service rules which will enable the grant of all qualified applications. With regard to the VHF/UHF systems, the Advisory Committee submitted a consensus report to the FCC. The process for the systems operating in the bands above 1 GHz involved more parties and more issues but still provided the FCC useful technical information to guide the adoption of rules for the new mobile satellite service.

  18. Design of a gigawatt space solar power satellite using optical concentrator system

    Science.gov (United States)

    Dessanti, B.; Komerath, N.; Shah, S.

    A 1-gigawatt space solar power satellite using a large array of individually pointable optical elements is identified as the key mass element of a large scale space solar power architecture using the Space Power Grid concept. The proposed satellite design enables a significant increase in specific power. Placed in sun-synchronous dynamic orbits near 2000km altitude, these satellites can maintain the constant solar view requirement of GEO-based architectures, while greatly reducing the beaming distance required, decreasing the required antenna size and in turn the overall system mass. The satellite uses an array of individually pointable optical elements (which we call a Mirasol Concentrator Array) to concentrate solar energy to an intensified feed target that feeds into the main heater of the spacecraft, similar conceptually to heliostat arrays. The spacecraft then utilizes Brayton cycle conversion to take advantage of non-linear power level scaling in order to generate high specific power values. Using phase array antennas, the power is then beamed at a millimeter wave frequency of 220GHz down to Earth. The design of the Mirasol concentrator system will be described and a detailed mass estimation of the system is developed. The technical challenges of pointing the elements and maintaining constant solar view is investigated. An end-to-end efficiency analysis is performed. Subsystem designs for the spacecraft are outlined. A detailed mass budget is refined to reflect reductions in uncertainty of the spacecraft mass, particularly in the Mirasol system. One of the key mass drivers of the spacecraft is the active thermal control system. The design of a lightweight thermal control system utilizing graphene sheets is also detailed.

  19. Periodic solutions of planetary systems with satellites and the averaging method in systems with fast and slow variables

    CERN Document Server

    Kudryavtseva, Elena A

    2012-01-01

    We study the partial case of the planar $N+1$ body problem, $N\\ge2$, of the type of planetary system with satellites. We assume that one of the bodies (the Sun) is much heavier than the other bodies ("planets" and "satellites"), moreover the planets are much heavier than the satellites, and the "years" are much longer than the "months". We prove that, under a nondegeneracy condition which in general holds, there exist at least $2^{N-2}$ smooth 2-parameter families of symmetric periodic solutions in a rotating coordinate system such that the distances between each planet and its satellites are much shorter than the distances between the Sun and the planets. We describe generating symmetric periodic solutions and prove that the nondegeneracy condition is necessary. We give sufficient conditions for some periodic solutions to be orbitally stable in linear approximation. Via the averaging method, the results are extended to a class of Hamiltonian systems with fast and slow variables close to the systems of semi-d...

  20. Land Mobile Satellite Service (LMSS): A conceptual system design and identification of the critical technologies. Part 1: Executive summary

    Science.gov (United States)

    Naderi, F. (Editor)

    1982-01-01

    A system design for a satellite aided land mobile service is described. The advanced system is based on a geostationary satellite which employs a large UHF reflector to communicate with small user antennas on mobile vehicles. It is shown that the system through multiple beam antennas and frequency reuse provides for radiotelephone and dispatch channels. It is concluded that the system is technologically feasible to provide service to rural and remote regions.

  1. Global navigation satellite systems: report of a joint workshop of the National Academy of Engineering and the Chinese Academy of Engineering

    National Research Council Canada - National Science Library

    Davis, Lance A; Enge, Per; Gao, Grace X

    2012-01-01

    ...: improved safety of life, increased productivity, and wide-spread convenience. Global navigation satellite systems summarizes the joint workshop on Global Navigation Satellite Systems held jointly by the U.S...

  2. Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou.

    Science.gov (United States)

    Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

    2015-02-09

    The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments.

  3. A space weather forecasting system with multiple satellites based on a self-recognizing network.

    Science.gov (United States)

    Tokumitsu, Masahiro; Ishida, Yoshiteru

    2014-05-05

    This paper proposes a space weather forecasting system at geostationary orbit for high-energy electron flux (>2 MeV). The forecasting model involves multiple sensors on multiple satellites. The sensors interconnect and evaluate each other to predict future conditions at geostationary orbit. The proposed forecasting model is constructed using a dynamic relational network for sensor diagnosis and event monitoring. The sensors of the proposed model are located at different positions in space. The satellites for solar monitoring equip with monitoring devices for the interplanetary magnetic field and solar wind speed. The satellites orbit near the Earth monitoring high-energy electron flux. We investigate forecasting for typical two examples by comparing the performance of two models with different numbers of sensors. We demonstrate the prediction by the proposed model against coronal mass ejections and a coronal hole. This paper aims to investigate a possibility of space weather forecasting based on the satellite network with in-situ sensing.

  4. A Space Weather Forecasting System with Multiple Satellites Based on a Self-Recognizing Network

    Directory of Open Access Journals (Sweden)

    Masahiro Tokumitsu

    2014-05-01

    Full Text Available This paper proposes a space weather forecasting system at geostationary orbit for high-energy electron flux (>2 MeV. The forecasting model involves multiple sensors on multiple satellites. The sensors interconnect and evaluate each other to predict future conditions at geostationary orbit. The proposed forecasting model is constructed using a dynamic relational network for sensor diagnosis and event monitoring. The sensors of the proposed model are located at different positions in space. The satellites for solar monitoring equip with monitoring devices for the interplanetary magnetic field and solar wind speed. The satellites orbit near the Earth monitoring high-energy electron flux. We investigate forecasting for typical two examples by comparing the performance of two models with different numbers of sensors. We demonstrate the prediction by the proposed model against coronal mass ejections and a coronal hole. This paper aims to investigate a possibility of space weather forecasting based on the satellite network with in-situ sensing.

  5. IoSiS: a radar system for imaging of satellites in space

    Science.gov (United States)

    Jirousek, M.; Anger, S.; Dill, S.; Schreiber, E.; Peichl, M.

    2017-05-01

    Space debris nowadays is one of the main threats for satellite systems especially in low earth orbit (LEO). More than 700,000 debris objects with potential to destroy or damage a satellite are estimated. The effects of an impact often are not identifiable directly from ground. High-resolution radar images are helpful in analyzing a possible damage. Therefor DLR is currently developing a radar system called IoSiS (Imaging of Satellites in Space), being based on an existing steering antenna structure and our multi-purpose high-performance radar system GigaRad for experimental investigations. GigaRad is a multi-channel system operating at X band and using a bandwidth of up to 4.4 GHz in the IoSiS configuration, providing fully separated transmit (TX) and receive (RX) channels, and separated antennas. For the observation of small satellites or space debris a highpower traveling-wave-tube amplifier (TWTA) is mounted close to the TX antenna feed. For the experimental phase IoSiS uses a 9 m TX and a 1 m RX antenna mounted on a common steerable positioner. High-resolution radar images are obtained by using Inverse Synthetic Aperture Radar (ISAR) techniques. The guided tracking of known objects during overpass allows here wide azimuth observation angles. Thus high azimuth resolution comparable to the range resolution can be achieved. This paper outlines technical main characteristics of the IoSiS radar system including the basic setup of the antenna, the radar instrument with the RF error correction, and the measurement strategy. Also a short description about a simulation tool for the whole instrument and expected images is shown.

  6. An Autonomous Satellite Time Synchronization System Using Remotely Disciplined VC-OCXOs

    Directory of Open Access Journals (Sweden)

    Xiaobo Gu

    2015-07-01

    Full Text Available An autonomous remote clock control system is proposed to provide time synchronization and frequency syntonization for satellite to satellite or ground to satellite time transfer, with the system comprising on-board voltage controlled oven controlled crystal oscillators (VC-OCXOs that are disciplined to a remote master atomic clock or oscillator. The synchronization loop aims to provide autonomous operation over extended periods, be widely applicable to a variety of scenarios and robust. A new architecture comprising the use of frequency division duplex (FDD, synchronous time division (STDD duplex and code division multiple access (CDMA with a centralized topology is employed. This new design utilizes dual one-way ranging methods to precisely measure the clock error, adopts least square (LS methods to predict the clock error and employs a third-order phase lock loop (PLL to generate the voltage control signal. A general functional model for this system is proposed and the error sources and delays that affect the time synchronization are discussed. Related algorithms for estimating and correcting these errors are also proposed. The performance of the proposed system is simulated and guidance for selecting the clock is provided.

  7. Optimization of Joint Power and Bandwidth Allocation in Multi-Spot-Beam Satellite Communication Systems

    Directory of Open Access Journals (Sweden)

    Heng Wang

    2014-01-01

    Full Text Available Multi-spot-beam technique has been widely applied in modern satellite communication systems. However, the satellite power and bandwidth resources in a multi-spot-beam satellite communication system are scarce and expensive; it is urgent to utilize the resources efficiently. To this end, dynamically allocating the power and bandwidth is an available way. This paper initially formulates the problem of resource joint allocation as a convex optimization problem, taking into account a compromise between the maximum total system capacity and the fairness among the spot beams. A joint bandwidth and power allocation iterative algorithm based on duality theory is then proposed to obtain the optimal solution of this optimization problem. Compared with the existing separate bandwidth or power optimal allocation algorithms, it is shown that the joint allocation algorithm improves both the total system capacity and the fairness among spot beams. Moreover, it is easy to be implemented in practice, as the computational complexity of the proposed algorithm is linear with the number of spot beams.

  8. Implementation of a Global Navigation Satellite System (GNSS) Augmentation to Tsunami Early Warning Systems

    Science.gov (United States)

    LaBrecque, John

    2016-04-01

    The Global Geodetic Observing System has issued a Call for Participation to research scientists, geodetic research groups and national agencies in support of the implementation of the IUGG recommendation for a Global Navigation Satellite System (GNSS) Augmentation to Tsunami Early Warning Systems. The call seeks to establish a working group to be a catalyst and motivating force for the definition of requirements, identification of resources, and for the encouragement of international cooperation in the establishment, advancement, and utilization of GNSS for Tsunami Early Warning. During the past fifteen years the populations of the Indo-Pacific region experienced a series of mega-thrust earthquakes followed by devastating tsunamis that claimed nearly 300,000 lives. The future resiliency of the region will depend upon improvements to infrastructure and emergency response that will require very significant investments from the Indo-Pacific economies. The estimation of earthquake moment magnitude, source mechanism and the distribution of crustal deformation are critical to rapid tsunami warning. Geodetic research groups have demonstrated the use of GNSS data to estimate earthquake moment magnitude, source mechanism and the distribution of crustal deformation sufficient for the accurate and timely prediction of tsunamis generated by mega-thrust earthquakes. GNSS data have also been used to measure the formation and propagation of tsunamis via ionospheric disturbances acoustically coupled to the propagating surface waves; thereby providing a new technique to track tsunami propagation across ocean basins, opening the way for improving tsunami propagation models, and providing accurate warning to communities in the far field. These two new advancements can deliver timely and accurate tsunami warnings to coastal communities in the near and far field of mega-thrust earthquakes. This presentation will present the justification for and the details of the GGOS Call for

  9. Reusable Reentry Satellite (RRS) system design study. Phase B, appendix E: Attitude control system study

    Science.gov (United States)

    1991-01-01

    A study which consisted of a series of design analyses for an Attitude Control System (ACS) to be incorporated into the Re-usable Re-entry Satellite (RRS) was performed. The main thrust of the study was associated with defining the control laws and estimating the mass and power requirements of the ACS needed to meet the specified performance goals. The analyses concentrated on the different on-orbit control modes which start immediately after the separation of the RRS from the launch vehicle. The three distinct on-orbit modes considered for these analyses are as follows: (1) Mode 1 - A Gravity Gradient (GG) three-axis stabilized spacecraft with active magnetic control; (2) Mode 2 - A GG stabilized mode with a controlled yaw rotation rate ('rotisserie') using three-axis magnetic control and also incorporating a 10 N-m-s momentum wheel along the (Z) yaw axis; and (3) Mode 3 - A spin stabilized mode of operation with the spin about the pitch (Y) axis, incorporating a 20 N-m-s momentum wheel along the pitch (Y) axis and attitude control via thrusters. To investigate the capabilities of the different controllers in these various operational modes, a series of computer simulations and trade-off analyses have been made to evaluate the achievable performance levels, and the necessary mass and power requirements.

  10. Methods of Celestial Mechanics Volume II: Application to Planetary System, Geodynamics and Satellite Geodesy

    CERN Document Server

    Beutler, Gerhard

    2005-01-01

    G. Beutler's Methods of Celestial Mechanics is a coherent textbook for students as well as an excellent reference for practitioners. Volume II is devoted to the applications and to the presentation of the program system CelestialMechanics. Three major areas of applications are covered: (1) Orbital and rotational motion of extended celestial bodies. The properties of the Earth-Moon system are developed from the simplest case (rigid bodies) to more general cases, including the rotation of an elastic Earth, the rotation of an Earth partly covered by oceans and surrounded by an atmosphere, and the rotation of an Earth composed of a liquid core and a rigid shell (Poincaré model). (2) Artificial Earth Satellites. The oblateness perturbation acting on a satellite and the exploitation of its properties in practice is discussed using simulation methods (CelestialMechanics) and (simplified) first order perturbation methods. The perturbations due to the higher-order terms of the Earth's gravitational potential and reso...

  11. Famine Early Warning Systems and Their Use of Satellite Remote Sensing Data

    Science.gov (United States)

    Brown, Molly E.; Essam, Timothy; Leonard, Kenneth

    2011-01-01

    Famine early warning organizations have experience that has much to contribute to efforts to incorporate climate and weather information into economic and political systems. Food security crises are now caused almost exclusively by problems of food access, not absolute food availability, but the role of monitoring agricultural production both locally and globally remains central. The price of food important to the understanding of food security in any region, but it needs to be understood in the context of local production. Thus remote sensing is still at the center of much food security analysis, along with an examination of markets, trade and economic policies during food security analyses. Technology including satellite remote sensing, earth science models, databases of food production and yield, and modem telecommunication systems contributed to improved food production information. Here we present an econometric approach focused on bringing together satellite remote sensing and market analysis into food security assessment in the context of early warning.

  12. Effects of rubber shock absorber on the flywheel micro vibration in the satellite imaging system

    Science.gov (United States)

    Deng, Changcheng; Mu, Deqiang; Jia, Xuezhi; Li, Zongxuan

    2016-12-01

    When a satellite is in orbit, its flywheel will generate micro vibration and affect the imaging quality of the camera. In order to reduce this effect, a rubber shock absorber is used, and a numerical model and an experimental setup are developed to investigate its effect on the micro vibration in the study. An integrated model is developed for the system, and a ray tracing method is used in the modeling. The spot coordinates and displacements of the image plane are obtained, and the modulate transfer function (MTF) of the system is calculated. A satellite including a rubber shock absorber is designed, and the experiments are carried out. Both simulation and experiments results show that the MTF increases almost 10 %, suggesting the rubber shock absorber is useful to decrease the flywheel vibration.

  13. Feasibility study of a solar power satellite system configured by formation flying

    Energy Technology Data Exchange (ETDEWEB)

    Takeichi, Noboru; Ueno, Hiroshi; Oda, Mitsushige [Japan Aerospace Exploration Agency (JAXA), Inst. of Space Technology and Aeronautics, Tsukuba, Ibaraki (Japan)

    2005-11-15

    This paper presents a new concept of a solar power satellite system configured by formation flying. In this concept, the solar power satellite system consists of sunlight reflectors and an energy generator-transmitter. The energy generator- transmitter is on a common GEO, and the reflectors are placed on the north and south by using solar pressure to raise their orbits from GEO. Therefore, the orbits of the reflectors and that of the energy generator-transmitter make three parallel GEOs. The feasibility of the concept and its requirements are also discussed, focusing on the orbital and attitude mechanics of the reflector. Because the tilt angle of the sunlight changes with the turning of the seasons, it is sometimes necessary to raise the orbit by thrusters especially around the solstice. For attitude dynamics, spin stabilization and thruster control are discussed as the attitude control strategies against the gravity gradient torque, which acts as a persistent periodic disturbance. (Author)

  14. Autonomous Rubidium Clock Weak Frequency Jump Detector for Onboard Navigation Satellite System.

    Science.gov (United States)

    Khare, Akshay; Arora, Rajat; Banik, Alak; Mehta, Sanjay D

    2016-02-01

    Frequency jumps are common in rubidium frequency sources. They affect the estimation of user position in navigational satellite systems. These jumps must be detected and corrected immediately as they have direct impact on the navigation system integrity. A novel weak frequency jump detector is proposed based on a Kalman filter with a multi-interval approach. This detector can be applied for both "sudden" and "slow" frequency transitions. In this detection method, noises of clock data are reduced by Kalman filtering, for accurate estimation of jump size with less latency. Analysis on in-orbit rubidium atomic frequency standard (RAFS) phase telemetry data shows that the detector can be used for fast detection and correction of weak frequency jumps. Furthermore, performance comparison of different existing frequency jump detection techniques with the proposed detector is discussed. A multialgorithm-based strategy is proposed depending on the jump size and latency for onboard navigation satellites having RAFS as the primary frequency source.

  15. Coherent receiving efficiency in satellite-ground coherent laser communication system based on analysis of polarization

    Science.gov (United States)

    Hao, Shiqi; Zhang, Dai; Zhao, Qingsong; Wang, Lei; Zhao, Qi

    2017-06-01

    Aimed at analyzing the coherent receiving efficiency of a satellite-ground coherent laser communication system, polarization state of the received light is analyzed. We choose the circularly polarized, partially coherent laser as transmitted light source. The analysis process includes 3 parts. Firstly, an theoretical model to analyze received light's polarization state is constructed based on Gaussian-Schell model (GSM) and cross spectral density function matrix. Then, analytic formulas to calculate coherent receiving efficiency are derived in which both initial ellipticity modification and deflection angle between polarization axes of the received light and the intrinsic light are considered. At last, numerical simulations are operated based on our study. The research findings investigate variations of polarization state and obtain analytic formulas to calculate the coherent receiving efficiency. Our study has theoretical guiding significances in construction and optimization of satellite-ground coherent laser communication system.

  16. Kinematic Precise Point Positioning Using Multi-Constellation Global Navigation Satellite System (GNSS Observations

    Directory of Open Access Journals (Sweden)

    Xidong Yu

    2017-01-01

    Full Text Available Multi-constellation global navigation satellite systems (GNSSs are expected to enhance the capability of precise point positioning (PPP by improving the positioning accuracy and reducing the convergence time because more satellites will be available. This paper discusses the performance of multi-constellation kinematic PPP based on a multi-constellation kinematic PPP model, Kalman filter and stochastic models. The experimental dataset was collected from the receivers on a vehicle and processed using self-developed software. A comparison of the multi-constellation kinematic PPP and real-time kinematic (RTK results revealed that the availability, positioning accuracy and convergence performance of the multi-constellation kinematic PPP were all better than those of both global positioning system (GPS-based PPP and dual-constellation PPP. Multi-constellation kinematic PPP can provide a positioning service with centimetre-level accuracy for dynamic users.

  17. A hybrid hopfield network-simulated annealing approach for frequency assignment in satellite communications systems.

    Science.gov (United States)

    Salcedo-Sanz, Sancho; Santiago-Mozos, Ricardo; Bousoño-Calzón, Carlos

    2004-04-01

    A hybrid Hopfield network-simulated annealing algorithm (HopSA) is presented for the frequency assignment problem (FAP) in satellite communications. The goal of this NP-complete problem is minimizing the cochannel interference between satellite communication systems by rearranging the frequency assignment, for the systems can accommodate the increasing demands. The HopSA algorithm consists of a fast digital Hopfield neural network which manages the problem constraints hybridized with a simulated annealing which improves the quality of the solutions obtained. We analyze the problem and its formulation, describing and discussing the HopSA algorithm and solving a set of benchmark problems. The results obtained are compared with other existing approaches in order to show the performance of the HopSA approach.

  18. TELE-X and its role in a future operational Nordic satellite system

    Science.gov (United States)

    Anderson, Lars

    In the middle of 1987 it is planned to launch TELE-X, the first Nordic telecommunications satellite. The Swedish-Norwegian company NOTELSAT (Nordic Telecommunications Satellite Corporation) will be responsible for the operation of the TELE-X system. Via the experimental TELE-X satellite the Nordic countries will get access to direct broadcasting of two TV-programs and at least four digital sound programs in stereo by use of two transponders in the 12.2 to 12.5 GHz band. The programs are planned to be composed of nationally produced programs in Norway. Sweden and Finland. By means of distributing these programs via satellite they will reach up to 4 times as many viewers and listernes as presently in the terrestrial national systems. The basic motivations for exchanging programs are to strengthen the cultural ties between the Nordic countries and to give the individuals more freedom in the choice of programs. Another goal is to give the public a better sound and picture quality than can be achieved today. These quality improvements shall be met by using small receiver parabolas of less than 1 m in diameter. Contributing to the improved quality is the choice of the C-MAC (Multiplexed Analoque Components) modulation system. TELE-X is a multipurpose satellite which besides the two TV-transponders will have two transponders for data/video communication in the frequency band 12.5 to 12.75 GHz. The choice of system for data and video is based on the philosophy of thin-route traffic between small and low cost earth stations (1.8 to 2.5 m) placed directly at the subscribers premises. The system includes an advanced Data/Video Control Station which automatically connects the traffic stations with standarized transmission speeds up to 2 Mbps. The system which is based on the SCPC/DAMA method can be expanded up to 5000 traffic stations. Numerous data/video applications will be investigated in the initial experimental phase of the project which also will be used for market

  19. Preliminary benefits study for a public service communications satellite system: Task order 2

    Science.gov (United States)

    1978-01-01

    The economic and social benefits to accrue from an operational public service communications satellite system are estimated for the following applications: teleradiology, emergency medical services, teleconferencing for both civilian and defense agencies, data transfer, remote cardiac monitoring, teleconsultation, continuing education for professionals, and severe storm warning. The potential impact of improved communication on the cost and quality of services are assessed for various agencies, professions, and industries.

  20. The integrated cryogenic system for the atmospheric vertical interferometric detector on FY-4 satellite

    Science.gov (United States)

    Wu, Yinong; Liu, EnGuang; Jiang, Zhenhua; Yang, Baoyu; Mu, Yongbin

    2016-05-01

    The cryogenic system for the atmospheric vertical interferometric detector on FY-4 satellite includes a Stirling cryocooler, a radiant cooler, a cryogenic heat pipe and some flexible thermal links as well. These cryogenic elements were integrated together in order to decrease the background radiation and maximize the sensitivity with high efficiency and high reliability. This paper summarizes the cryogenic integration design, technical challenges, and the results of thermal and performance testing.

  1. Model of the Availability of Satellite Navigational Systems Asg-Eupos and Rtk Services in Poland

    Science.gov (United States)

    Oszczak, Bartlomiej; Maciejczyk, Olga

    Geodetic precision gravity field satellite missions are to determine Earth gravity field with a high spatial resolution and accuracy. In order to carry out a successful gravity field stallite mission non-gravitational forces acting upon the spacecraft need to be either compensated or measured and thereafter corrected as they distort the actual gravity signal. These non-gravitational forces can be detected and determined by an onboard accelerometer. However, in many cases not only non-gravitational effects are detected, but also noise signals which are self-induced by the satellites onboard instruments. This study shall give a brief overview about the effects acting upon geodetic precision space laboratories, that ought to be regarded in order to realise a smooth functioning of a gravity field mission. Abstract In this study the focus will be upon the GRACE (Gravity Recovery And Climate Experiment) gravity field satellite mission, concerning the impacts that onboard instruments used for attitude and orbit control as well as thermal control have onto the accelerometer and what impact this can have onto the gravity field determined by the GRACE twin satellites. As the GRACE twin satellites can only operate successfully if they are maintained in the same orbit and in a certrain orientation to each other, the Attitude and Orbit Control System (AOCS) is mandatory. This AOCS determines whether the onboard cold-gas thrusters, which are used for both orbit and attitude recovery, are fired and also the duration of the firing event. Moreover, the AOCS controls the three onboard magnetic torquers, which only can be used for attitude restorage. The acceleration disturbances induced by instruments for attitude and orbit restorage can be as high as 20 nm/s2 due to magnetic torquer activity and 0.6 µm/s2 due to thruster firing events.

  2. Assessment for Operator Confidence in Automated Space Situational Awareness and Satellite Control Systems

    Science.gov (United States)

    Gorman, J.; Voshell, M.; Sliva, A.

    2016-09-01

    The United States is highly dependent on space resources to support military, government, commercial, and research activities. Satellites operate at great distances, observation capacity is limited, and operator actions and observations can be significantly delayed. Safe operations require support systems that provide situational understanding, enhance decision making, and facilitate collaboration between human operators and system automation both in-the-loop, and on-the-loop. Joint cognitive systems engineering (JCSE) provides a rich set of methods for analyzing and informing the design of complex systems that include both human decision-makers and autonomous elements as coordinating teammates. While, JCSE-based systems can enhance a system analysts' understanding of both existing and new system processes, JCSE activities typically occur outside of traditional systems engineering (SE) methods, providing sparse guidance about how systems should be implemented. In contrast, the Joint Director's Laboratory (JDL) information fusion model and extensions, such as the Dual Node Network (DNN) technical architecture, provide the means to divide and conquer such engineering and implementation complexity, but are loosely coupled to specialized organizational contexts and needs. We previously describe how Dual Node Decision Wheels (DNDW) extend the DNN to integrate JCSE analysis and design with the practicalities of system engineering and implementation using the DNN. Insights from Rasmussen's JCSE Decision Ladders align system implementation with organizational structures and processes. In the current work, we present a novel approach to assessing system performance based on patterns occurring in operational decisions that are documented by JCSE processes as traces in a decision ladder. In this way, system assessment is closely tied not just to system design, but the design of the joint cognitive system that includes human operators, decision-makers, information systems, and

  3. Parameter Impact on Sharing Studies Between UAS CNPC Satellite Transmitters and Terrestrial Systems

    Science.gov (United States)

    Kerczewski, Robert J.; Wilson, Jeffrey D.; Bishop, William D.

    2015-01-01

    In order to provide a control and non-payload communication (CNPC) link for civil-use unmanned aircraft systems (UAS) when operating in beyond-line-of-sight (BLOS) conditions, satellite communication links are generally required. The International Civil Aviation Organization (ICAO) has determined that the CNPC link must operate over protected aviation safety spectrum allocations. Although a suitable allocation exists in the 5030-5091 MHz band, no satellites provide operations in this band and none are currently planned. In order to avoid a very lengthy delay in the deployment of UAS in BLOS conditions, it has been proposed to use existing satellites operating in the Fixed Satellite Service (FSS), of which many operate in several spectrum bands. Regulatory actions by the International Telecommunications Union (ITU) are needed to enable such a use on an international basis, and indeed Agenda Item (AI) 1.5 for the 2015 World Radiocommunication Conference (WRC) was established to decide on the enactment of possible regulatory provisions. As part of the preparation for AI 1.5, studies on the sharing FSS bands between existing services and CNPC for UAS are being contributed by NASA and others. These studies evaluate the potential impact of satellite CNPC transmitters operating from UAS on other in-band services, and on the potential impact of other in-band services on satellite CNPC receivers operating on UAS platforms. Such studies are made more complex by the inclusion of what are essentially moving FSS earth stations, compared to typical sharing studies between fixed elements. Hence, the process of determining the appropriate technical parameters for the studies meets with difficulty. In order to enable a sharing study to be completed in a less-than-infinite amount of time, the number of parameters exercised must be greatly limited. Therefore, understanding the impact of various parameter choices is accomplished through selectivity analyses. In the case of sharing

  4. Remote sensing application system for water environments developed for Environment Satellite 1

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Remote sensing data collected by the Environment Satellite I are characterized by high temporal resolution,high spectral resolution and mid-high spatial resolution.We designed the Remote Sensing Application System for Water Environments(RSASWE) to create an integrated platform for remote sensing data processing,parameter information extraction and thematic mapping using both remote sensing and GIS technologies.This system provides support for regional water environmental monitoring,and prediction and warning of water pollution.Developed to process and apply data collected by Environment Satellite I,this system has automated procedures including clipping,observation geometry computation,radiometric calibration,6S atmospheric correction and water quality parameter inversion.RSASWE consists of six subsystems:remote sensing image processing,basic parameter inversion,water environment remote sensing thematic outputs,application outputs,automated water environment outputs and a non-point source pollution monitoring subsystem.At present RSASWE plays an important role in operations at the Satellite Environment Center.

  5. Characterization of interfade duration for satellite communication systems design and optimization in a temperate climate

    Science.gov (United States)

    Jorge, Flávio; Riva, Carlo; Rocha, Armando

    2016-03-01

    The characterization of the fade dynamics on Earth-satellite links is an important subject when designing the so called fade mitigation techniques that contribute to the proper reliability of the satellite communication systems and the customers' quality of service (QoS). The interfade duration, defined as the period between two consecutive fade events, has been only poorly analyzed using limited data sets, but its complete characterization would enable the design and optimization of the satellite communication systems by estimating the system requirements to recover in time before the next propagation impairment. Depending on this analysis, several actions can be taken ensuring the service maintenance. In this paper we present for the first time a detailed and comprehensive analysis of the interfade events statistical properties based on 9 years of in-excess attenuation measurements at Ka band (19.7 GHz) with very high availability that is required to build a reliable data set mainly for the longer interfade duration events. The number of years necessary to reach the statistical stability of interfade duration is also evaluated for the first time, providing a reference when accessing the relevance of the results published in the past. The study is carried out in Aveiro, Portugal, which is conditioned by temperate Mediterranean climate with Oceanic influences.

  6. The earth radiation budget satellite system of the early 1980's

    Science.gov (United States)

    Cooper, J. E.; Woerner, C. V.

    1978-01-01

    The overall program objective of the Earth Radiation Budget Satellite System is to gather the required radiation budget data and apply these data for a better understanding and prediction of climate. The paper describes the planned system, including the instruments and the associated sampling strategies and data analysis methods. Examination of mission implications reveals the need for a multisensor, multisatellite system consisting of high- and mid-inclination orbits. Each spacecraft will carry wide and medium field-of-view sensors, a sensor for measuring the solar constant, and a narrow field-of-view cross-track scanner.

  7. A modeling and simulation of control system of satellite tracking platform an- tenna

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaojun; GONG Lihong

    2012-01-01

    Based on the platform of mobile carrier satellite tracking has a wide range of applications. The paper adopts the advanced method of to step response identify, using the data obtained by the experiment model of high-speed acquisition, using the method of the least squares, finally the antenna control system model function was identified. Make use of integral separation algorithm, simu- link simulation and experiment analysis to set the control parameters of it. Stimulate the signal antenna control system under inter- fering. The experiment of the simulation experiment showed that the antenna control system model is stable with little error.

  8. Health and safety. Preliminary comparative assessment of the satellite power system (SPS) and other energy alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Habegger, L.J.; Gasper, J.R.; Brown, C.D.

    1980-04-01

    Existing data on the health and safety risks of a satellite power system and four electrical generation systems are analyzed: a combined-cycle coal power system with a low-Btu gasifier and open-cycle gas turbine, a fission power system with fuel reprocessing, a central-station, terrestrial, solar-photovoltaic power system, and a first-generation design for a fusion power system. The systems are compared on the basis of expected deaths and person-days lost per year associated with 1000 MW of average electricity generation and the number of health and safety risks that are identified as potentially significant but unquantifiable. The appendices provide more detailed information on risks, uncertainties, additional research needed, and references for the identified impacts of each system.

  9. Intelligent remote sensing satellite system%智能遥感卫星系统

    Institute of Scientific and Technical Information of China (English)

    张兵

    2011-01-01

    分析了当前遥感卫星系统存在的一些不足,论述了新一代"智能遥感卫星系统"的概念及其主要特点,对其中自适应遥感成像和星上数据实时处理两个核心部分进行重点介绍,并对其涉及的关键科学问题和关键技术进行阐述.设计了一套具有自适应成像和应用模式优化能力的智能高光谱卫星有效载荷系统.该系统由用于区域背景信息获取的前视预判遥感器、用于地表详细观测的主遥感器以及星上数据实时处理和分析3部分组成.对智能高光谱卫星的工作原理和流程进行介绍,并呼吁中国尽快围绕智能遥感卫星系统开展一些前沿性的科学理论和关键技术研究,以实现中国在卫星遥感领域的跨越式发展.%This paper analyzes the disadvantages of the current remote sensing satellite systems, and describes the concept of the latest generation "intelligent remote sensing satellite system" and its main characteristics which mainly includes: (1) the adaptive remote sensor system; (2) the onboard real-time data processing system; and also introduces the key scientific issues and the key technologies involved. This paper presents the design of an intelligent hyperspectral sateUite payload system with adaptive imaging and application mode optimization capacity, which consists of three parts: (1) a fore-field pfe-judgment sensor for regional background information acquisition; (2) a main sensor for detailed surface observations; (3) an onboard real-time data processing and analysis subsystem. It also introduces the working principles and processes of intelligent hyperspectral satellite,and calls for the research on some frontier scientific theories and key technologies related to the intelligent remote sensing satelLite system in an early stage to realize the leap-forward development in the field of remote sensing satellite in China.

  10. Monitoring and remote failure detection of grid-connected PV systems based on satellite observations

    Energy Technology Data Exchange (ETDEWEB)

    Drews, A.; Lorenz, E.; Betcke, J.; Heinemann, D. [Oldenburg University, Institute of Physics, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany); de Keizer, A.C.; van Sark, W.G.J.H.M. [University of Utrecht, Copernicus Institute, Department of Science, Technology, and Society, Heidelberglaan 2, 3584 CH Utrecht (Netherlands); Beyer, H.G. [University of Applied Sciences Magdeburg-Stendal (FH), Institute of Electrical Engineering, Breitscheidstr. 2, 39114 Magdeburg (Germany); Heydenreich, W.; Wiemken, E. [Fraunhofer Institute for Solar Energy Systems, Heidenhofstr. 2, 79110 Freiburg (Germany); Stettler, S.; Toggweiler, P. [Enecolo AG, Lindhofstr. 52, 8617 Moenchaltorf (Switzerland); Bofinger, S.; Schneider, M.; Heilscher, G. [Meteocontrol GmbH, Spicherer Strasse 48, 86157 Augsburg (Germany)

    2007-04-15

    Small grid-connected photovoltaic systems up to 5 kW{sub p} are often not monitored because advanced surveillance systems are not economical. Hence, some system failures which lead to partial energy losses stay unnoticed for a long time. Even a failure that results in a larger energy deficit can be difficult to detect by PV laymen due to the fluctuating energy yields. Within the EU project PVSAT-2, a fully automated performance check has been developed to assure maximum energy yields and to optimize system maintenance for small grid-connected PV systems. The aim is the early detection of system malfunctions and changing operating conditions to prevent energy and subsequent financial losses for the operator. The developed procedure is based on satellite-derived solar irradiance information that replaces on-site measurements. In conjunction with a simulation model the expected energy yield of a PV system is calculated. In case of the occurrence of a defined difference between the simulated and actual energy yield, an automated failure detection routine searches for the most probable failure sources and notifies the operator. This paper describes the individual components of the developed procedure - the satellite-derived irradiance, the used PV simulation model, and the principles of the automated failure detection routine. Moreover, it presents results of an 8-months test phase with 100 PV systems in three European countries. (author)

  11. Clustering of tethered satellite system simulation data by an adaptive neuro-fuzzy algorithm

    Science.gov (United States)

    Mitra, Sunanda; Pemmaraju, Surya

    1992-01-01

    Recent developments in neuro-fuzzy systems indicate that the concepts of adaptive pattern recognition, when used to identify appropriate control actions corresponding to clusters of patterns representing system states in dynamic nonlinear control systems, may result in innovative designs. A modular, unsupervised neural network architecture, in which fuzzy learning rules have been embedded is used for on-line identification of similar states. The architecture and control rules involved in Adaptive Fuzzy Leader Clustering (AFLC) allow this system to be incorporated in control systems for identification of system states corresponding to specific control actions. We have used this algorithm to cluster the simulation data of Tethered Satellite System (TSS) to estimate the range of delta voltages necessary to maintain the desired length rate of the tether. The AFLC algorithm is capable of on-line estimation of the appropriate control voltages from the corresponding length error and length rate error without a priori knowledge of their membership functions and familarity with the behavior of the Tethered Satellite System.

  12. Formulation of geopotential difference determination using optical-atomic clocks onboard satellites and on ground based on Doppler cancellation system

    Science.gov (United States)

    Shen, Ziyu; Shen, Wen-Bin; Zhang, Shuangxi

    2016-08-01

    In this study, we propose an approach for determining the geopotential difference using high-frequency-stability microwave links between satellite and ground station based on Doppler cancellation system. Suppose a satellite and a ground station are equipped with precise optical-atomic clocks (OACs) and oscillators. The ground oscillator emits a signal with frequency fa towards the satellite and the satellite receiver (connected with the satellite oscillator) receives this signal with frequency fb which contains the gravitational frequency shift effect and other signals and noises. After receiving this signal, the satellite oscillator transmits and emits, respectively, two signals with frequencies fb and fc towards the ground station. Via Doppler cancellation technique, the geopotential difference between the satellite and the ground station can be determined based on gravitational frequency shift equation by a combination of these three frequencies. For arbitrary two stations on ground, based on similar procedures as described above, we may determine the geopotential difference between these two stations via a satellite. Our analysis shows that the accuracy can reach 1 m2 s- 2 based on the clocks' inaccuracy of about 10-17 (s s-1) level. Since OACs with instability around 10-18 in several hours and inaccuracy around 10-18 level have been generated in laboratory, the proposed approach may have prospective applications in geoscience, and especially, based on this approach a unified world height system could be realized with one-centimetre level accuracy in the near future.

  13. Tethered Satellites as an Enabling Platform for Operational Space Weather Monitoring Systems

    Science.gov (United States)

    Gilchrist, Brian E.; Krause, Linda Habash; Gallagher, Dennis Lee; Bilen, Sven Gunnar; Fuhrhop, Keith; Hoegy, Walt R.; Inderesan, Rohini; Johnson, Charles; Owens, Jerry Keith; Powers, Joseph; Voronka, Nestor; Williams, Scott

    2013-01-01

    Tethered satellites offer the potential to be an important enabling technology to support operational space weather monitoring systems. Space weather "nowcasting" and forecasting models rely on assimilation of near-real-time (NRT) space environment data to provide warnings for storm events and deleterious effects on the global societal infrastructure. Typically, these models are initialized by a climatological model to provide "most probable distributions" of environmental parameters as a function of time and space. The process of NRT data assimilation gently pulls the climate model closer toward the observed state (e.g., via Kalman smoothing) for nowcasting, and forecasting is achieved through a set of iterative semi-empirical physics-based forward-prediction calculations. Many challenges are associated with the development of an operational system, from the top-level architecture (e.g., the required space weather observatories to meet the spatial and temporal requirements of these models) down to the individual instruments capable of making the NRT measurements. This study focuses on the latter challenge: we present some examples of how tethered satellites (from 100s of m to 20 km) are uniquely suited to address certain shortfalls in our ability to measure critical environmental parameters necessary to drive these space weather models. Examples include long baseline electric field measurements, magnetized ionospheric conductivity measurements, and the ability to separate temporal from spatial irregularities in environmental parameters. Tethered satellite functional requirements are presented for two examples of space environment observables.

  14. The Joint Polar Satellite System (JPSS) Program's Algorithm Change Process (ACP): Past, Present and Future

    Science.gov (United States)

    Griffin, Ashley

    2017-01-01

    The Joint Polar Satellite System (JPSS) Program Office is the supporting organization for the Suomi National Polar Orbiting Partnership (S-NPP) and JPSS-1 satellites. S-NPP carries the following sensors: VIIRS, CrIS, ATMS, OMPS, and CERES with instruments that ultimately produce over 25 data products that cover the Earths weather, oceans, and atmosphere. A team of scientists and engineers from all over the United States document, monitor and fix errors in operational software code or documentation with the algorithm change process (ACP) to ensure the success of the S-NPP and JPSS 1 missions by maintaining quality and accuracy of the data products the scientific community relies on. This poster will outline the programs algorithm change process (ACP), identify the various users and scientific applications of our operational data products and highlight changes that have been made to the ACP to accommodate operating system upgrades to the JPSS programs Interface Data Processing Segment (IDPS), so that the program is ready for the transition to the 2017 JPSS-1 satellite mission and beyond.

  15. Power Allocation Algorithm for IDMA-based Multi-Beam Satellite Communication Systems

    Directory of Open Access Journals (Sweden)

    Gongliang Liu

    2012-08-01

    Full Text Available Rain attenuation is one of the most dominant impairment factors that degrade the performance of satellite communications at Ka band and above. In order to solve the technical bottlenecks in the existing Ka-band satellite communication schemes, the authors has introduced the emerging Interleave Division Multiple Access (IDMA technology into multi-beam satellite communication systems, and consequently, a novel power allocation algorithm is proposed for the emerging and promising system in this paper. The main goal of the proposed scheme is to provide sufficient transmission quality to as many mobiles as possible, even for the users suffering heavy rain attenuation. Analysis and simulation results show that compared to the traditional power allocation schemes, the proposed scheme can guarantee high power efficiency even in heavy rain attenuation conditions, illustrating the high efficiency of the Chip-by-Chip (CBC Multi-user Detection (MUD technique in IDMA. Furthermore, in virtue of the Signal to Interference plus Noise Ratio (SINR evolution technique, the proposed scheme can make accurate estimation of available resource on considering the effect of MUD, leading to low outage probability.

  16. Technology development of the Space Transportation System mission and terrestrial applications of satellite technology

    Science.gov (United States)

    1981-01-01

    The Space Transportation System (STS) is discussed, including the launch processing system, the thermal protection subsystem, meteorological research, sound supression water system, rotating service structure, improved hypergol or removal systems, fiber optics research, precision positioning, remote controlled solid rocket booster nozzle plugs, ground operations for Centaur orbital transfer vehicle, parachute drying, STS hazardous waste disposal and recycle, toxic waste technology and control concepts, fast analytical densitometry study, shuttle inventory management system, operational intercommunications system improvement, and protective garment ensemble. Terrestrial applications are also covered, including LANDSAT applications to water resources, satellite freeze forecast system, application of ground penetrating radar to soil survey, turtle tracking, evaluating computer drawn ground cover maps, sparkless load pulsar, and coupling a microcomputer and computing integrator with a gas chromatograph.

  17. Multiangle Bistatic SAR Imaging and Fusion Based on BeiDou-2 Navigation Satellite System

    Directory of Open Access Journals (Sweden)

    Zeng Tao

    2015-01-01

    Full Text Available Bistatic Synthetic Aperture Radar (BSAR based on the Global Navigation Service System (GNSSBSAR uses navigation satellites as radar transmitters, which are low in cost. However, GNSS-BSAR images have poor resolution and low Signal-to-Noise Ratios (SNR. In this paper, a multiangle observation and data processing strategy are presented based on BeiDou-2 navigation satellite imagery, from which twenty-six BSAR images in different configurations are obtained. A region-based fusion algorithm using region of interest segmentation is proposed, and a high-quality fusion image is obtained. The results reveal that the multiangle imaging method can extend the applications of GNSS-BSAR.

  18. Simultaneous state and actuator fault estimation for satellite attitude control systems

    Institute of Scientific and Technical Information of China (English)

    Cheng Yao; Wang Rixin; Xu Minqiang; Li Yuqing

    2016-01-01

    In this paper, a new nonlinear augmented observer is proposed and applied to satellite attitude control systems. The observer can estimate system state and actuator fault simultaneously. It can enhance the performances of rapidly-varying faults estimation. Only original system matrices are adopted in the parameter design. The considered faults can be unbounded, and the proposed augmented observer can estimate a large class of faults. Systems without disturbances and the fault whose finite times derivatives are zero piecewise are initially considered, followed by a discussion of a general situation where the system is subject to disturbances and the finite times derivatives of the faults are not null but bounded. For the considered nonlinear system, convergence conditions of the observer are provided and the stability analysis is performed using Lyapunov direct method. Then a feasible algorithm is explored to compute the observer parameters using linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed approach is illustrated by considering an example of a closed-loop satellite attitude control system. The simulation results show satisfactory perfor-mance in estimating states and actuator faults. It also shows that multiple faults can be estimated successfully.

  19. Post-launch operations and data production

    Science.gov (United States)

    Beech, P.; Meyer, D.

    1990-01-01

    Postlaunch operations scheduled in connection with the October 5, 1990, launch of Space Shuttle Discovery with the Ulysses payload are detailed. A summary is presented of postlaunch events up to and including the separation of Ulysses from Discovery, providing a timeline for the upper-stage burn and spacecraft separation. A timeline is also provided for the payload switch-on. Initial in-orbit and routine operations are discussed and missions-operations organization, the data ground segment, and Ulysses data production are considered.

  20. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Technical Performance Measures of the Block 2 Architecture

    Science.gov (United States)

    Grant, K. D.; Panas, M.

    2016-12-01

    NOAA and NASA are jointly acquiring the next-generation civilian weather satellite system: the Joint Polar Satellite System (JPSS). JPSS replaced the afternoon orbit component and ground processing of NOAA's old POES system. JPSS satellites carry sensors that collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a globally distributed, multi-mission system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture has been upgraded to Block 2.0 to satisfy several key objectives, including: "operationalizing" the first satellite, Suomi NPP, which originally was a risk reduction mission; leveraging lessons learned in multi-mission support, taking advantage of newer, more reliable and efficient technologies and satisfying constraints due of the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 48 Technical Performance Measures (TPMs) across 9 categories: Data Availability, Data Latency, Operational Availability, Margin, Scalability, Situational Awareness, Transition (between environments and sites), WAN Efficiency, and Data Recovery Processing. This paper will provide an overview of the CGS Block 2.0 architecture, with particular focus on the 9 TPM categories listed above. We will describe how we ensure the deployed architecture meets these TPMs to satisfy our multi-mission objectives with the deployment of Block 2.0.

  1. An Experimental Global Monitoring System for Rainfall-triggered Landslides using Satellite Remote Sensing Information

    Science.gov (United States)

    Hong, Yang; Adler, Robert F.; Huffman, George J.

    2006-01-01

    Landslides triggered by rainfall can possibly be foreseen in real time by jointly using rainfall intensity-duration thresholds and information related to land surface susceptibility. However, no system exists at either a national or a global scale to monitor or detect rainfall conditions that may trigger landslides due to the lack of extensive ground-based observing network in many parts of the world. Recent advances in satellite remote sensing technology and increasing availability of high-resolution geospatial products around the globe have provided an unprecedented opportunity for such a study. In this paper, a framework for developing an experimental real-time monitoring system to detect rainfall-triggered landslides is proposed by combining two necessary components: surface landslide susceptibility and a real-time space-based rainfall analysis system (http://trmm.gsfc.nasa.aov). First, a global landslide susceptibility map is derived from a combination of semi-static global surface characteristics (digital elevation topography, slope, soil types, soil texture, and land cover classification etc.) using a GIs weighted linear combination approach. Second, an adjusted empirical relationship between rainfall intensity-duration and landslide occurrence is used to assess landslide risks at areas with high susceptibility. A major outcome of this work is the availability of a first-time global assessment of landslide risk, which is only possible because of the utilization of global satellite remote sensing products. This experimental system can be updated continuously due to the availability of new satellite remote sensing products. This proposed system, if pursued through wide interdisciplinary efforts as recommended herein, bears the promise to grow many local landslide hazard analyses into a global decision-making support system for landslide disaster preparedness and risk mitigation activities across the world.

  2. System Critical Design Audit (CDA). Books 1, 2 and 3; [Small Satellite Technology Initiative (SSTI Lewis Spacecraft Program)

    Science.gov (United States)

    1995-01-01

    Small Satellite Technology Initiative (SSTI) Lewis Spacecraft Program is evaluated. Spacecraft integration, test, launch, and spacecraft bus are discussed. Payloads and technology demonstrations are presented. Mission data management system and ground segment are also addressed.

  3. Estimation of the demand for public services communications. [market research and economic analysis for a communications satellite system

    Science.gov (United States)

    1976-01-01

    Market analyses and economic studies are presented to support NASA planning for a communications satellite system to provide public services in health, education, mobile communications, data transfer, and teleconferencing.

  4. Controlling laser beam irradiation area using an optical duplicate system to improve satellite-ground laser communications

    Science.gov (United States)

    Nakayama, Tomoko; Takayama, Yoshihisa; Fujikawa, Chiemi; Kodate, Kashiko

    2016-08-01

    To improve the quality of ground to satellite laser communications, we propose an optical duplicate system of the optical ground station. Our proposed approach can be used to control the beam irradiation area for a satellite position without changing the total power of the output beam and the mechanical drive unit; this is performed by controlling the input pattern of a liquid crystal filter inserted in the input plane of the optical duplicate system. Most of the power of the diffracted laser beam emitted from the ground is focused on the optical axis. By distributing the power to side lobes, it is possible to extend the coverage area for a satellite position. This system allows the laser beam irradiation area to be controlled by a sufficient degree by adjusting the threshold of the satellite reception level. We verify the efficacy of the system using wave optics numerical calculations.

  5. The Innovative DE orbiting Aerobrake System "IDEAS " for Small Satellites: The Use of Gossamer Technolgy for a Cleaner Space

    Science.gov (United States)

    Santerre, B.; Bonnefond, T.; Dupuy, C.

    2008-08-01

    From the birth of space adventure until now, a huge number of objects have been put in orbit. Today, space environment is more and more crowded. The assessed number of objects sizing more than 1 cm is 300000. About 9600 objects are referenced, with only 500 useful. 22% of satellites are non operating satellites. For these reasons, space debris is becoming a real concern. The Inter Agency Space Debris Cordination (IDAC), composed of 11 space agencies, has defined a code of conduct to limit the space debris. In 2004, CNES decided to apply this code of conduct. As a consequence, the in-orbit life time (after operative life) of every satellite must be limited to 25 years. In the frame of this code of conduct, Astrium Space Transportation is developing in collaboration with CNES, a solution for slow deorbiting of small satellites using passive aerobraking. The Gossamer technology has been identified as the best solution to fulfil this functional requirement and to limit cost and performance impacts for the satellite. The interest of using gossamer technologies for small satellite aerobraking system was demonstrated by a feasibility study performed by Astrium Space Transportation during 2005. The main advantages of the retained solution are the easy accommodation on satellite, the simple electrical interface with the satellite, the ability to be operated even on an underperforming spacecraft (as long as telemetry can be received) and the absence of need of any specific satellite control. The trade-off between several inflatable technologies led to the selection of kapton/aluminium/kapton laminates, mainly because of the specific requirements of the mission (low available electrical power, long passive-life duration before deployment, no attitude control during deployment = non defined thermal conditions). This technology is currently developed and will be qualified for an application on a CNES satellite, called Microscope, that is asked to reduce its natural deorbiting

  6. EVALUATION OF POWER SPECTRAL DENSITY OF PASSIVE INTERMODULATION DISTORTION IN HIGH-POWER COMMUNICATION SATELLITE SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Zhang Shiquan; Ge Debiao

    2005-01-01

    In order to analyze the deleterious effects of Passive InterModulation (PIM) on high power communication satellite systems, the basic concept of PIM is introduced, and an equation for the power spectral density of the n-th order PIM distortion insuch systems is derived by applying flat signal-power spectrum assumption and Fourier transform method. It is indicated that PIM level generally decreases with order and the lowest frequency receive channel in the receive band is the channel of most affected by PIM interference.

  7. Influence of satellite vibration on radio over IsOWC system

    Science.gov (United States)

    Zong, Kang; Zhu, Jiang

    2017-07-01

    In this paper, we analyze the influence of satellite vibration on radio over intersatellite optical wireless communication (IsOWC) system with an optical booster amplifier (OBA) and an optical preamplifier. The closed-form expressions of radio frequency (RF) gain, noise figure (NF) and spurious-free dynamic range (SFDR) are derived in the presence of pointing jitter taking consideration of bias error. Numerical results for RF gain, NF and SFDR are given for demonstration. Results indicate that the bias error obviously deteriorates the performance of the radio over IsOWC system.

  8. Antenna pointing system for satellite tracking based on Kalman filtering and model predictive control techniques

    Science.gov (United States)

    Souza, André L. G.; Ishihara, João Y.; Ferreira, Henrique C.; Borges, Renato A.; Borges, Geovany A.

    2016-12-01

    The present work proposes a new approach for an antenna pointing system for satellite tracking. Such a system uses the received signal to estimate the beam pointing deviation and then adjusts the antenna pointing. The present work has two contributions. First, the estimation is performed by a Kalman filter based conical scan technique. This technique uses the Kalman filter avoiding the batch estimator and applies a mathematical manipulation avoiding the linearization approximations. Secondly, a control technique based on the model predictive control together with an explicit state feedback solution are obtained in order to reduce the computational burden. Numerical examples illustrate the results.

  9. Multi-user satellite communications system using an innovative compressive receiver

    Science.gov (United States)

    Staples, Edward J.

    1992-01-01

    There is a need for an onboard simultaneous multi-channel demodulation system for a satellite communications system. Studies indicate that Convolve Multiply Convolve (CMC) filtering with surface acoustic wave (SAW) dispersive delay lines will eliminate the necessity of onboard satellite channelized filters of complex fourier transform processors. The reason for choosing the CMC technique is its ability to perform Fourier transformations in a shorter time with less space and power consumption than digital Fourier transform processors. Each ground terminal in this multi-users communications system is remotely located and operates independently; hence, a method of synchronizing the transmission of these users is presented which utilizes the existing Global Positioning System (GPS) system. Each ground user is equipped with a low cost ground terminal that has a synchronization subsystem attached to it. The system design of an onboard Multi-channel Receiver and Demodulator utilizes Quadrature Phase Shift Keying (QPSK) as the modulation technique. This technique provides the best figure of merit, i.e., the lowest transmitter power requirement per communication channel.

  10. Development of satellite-based drought monitoring and warning system in Asian Pacific countries

    Science.gov (United States)

    Takeuchi, W.; Oyoshi, K.; Muraki, Y.

    2013-12-01

    This research focuses on a development of satellite-based drought monitoring warning system in Asian Pacific countries. Drought condition of cropland is evaluated by using Keeth-Byram Drought Index (KBDI) computed from rainfall measurements with GSMaP product, land surface temperature by MTSAT product and vegetation phenology by MODIS NDVI product at daily basis. The derived information is disseminated as a system for an application of space based technology (SBT) in the implementation of the Core Agriculture Support Program. The benefit of this system are to develop satellite-based drought monitoring and early warning system (DMEWS) for Asian Pacific counties using freely available data, and to develop capacity of policy makers in those countries to apply the developed system in policy making. A series of training program has been carried out in 2013 to officers and researchers of ministry of agriculture and relevant agencies in Greater Mekong Subregion countries including Cambodia, China, Myanmar, Laos, Thailand and Vietnam. This system is running as fully operational and can be accessed at http://webgms.iis.u-tokyo.ac.jp/DMEWS/.

  11. Health and safety: Preliminary comparative assessment of the Satellite Power System (SPS) and other energy alternatives

    Science.gov (United States)

    Habegger, L. J.; Gasper, J. R.; Brown, C.

    1980-01-01

    Data readily available from the literature were used to make an initial comparison of the health and safety risks of a fission power system with fuel reprocessing; a combined-cycle coal power system with a low-Btu gasifier and open-cycle gas turbine; a central-station, terrestrial, solar photovoltaic power system; the satellite power system; and a first-generation fusion system. The assessment approach consists of the identification of health and safety issues in each phase of the energy cycle from raw material extraction through electrical generation, waste disposal, and system deactivation; quantitative or qualitative evaluation of impact severity; and the rating of each issue with regard to known or potential impact level and level of uncertainty.

  12. Modeling Navigation System Performance of a Satellite-Observing Star Tracker Tightly Integrated with an Inertial Measurement Unit

    Science.gov (United States)

    2015-03-26

    Hancock, R.C. Stirbl, and B. Pain. “ Active pixel sensor (APS) based star tracker ”. Aerospace Conference, 1998 IEEE, volume 1, 119–127 vol.1. 1998...Modeling Navigation System Performance of a Satellite-Observing Star Tracker Tightly Integrated with an Inertial Measurement Unit DISSERTATION Scott...Navigation System Performance of a Satellite-Observing Star Tracker Tightly Integrated with an Inertial Measurement Unit DISSERTATION Presented to the

  13. Validation of the Global NASA Satellite-based Flood Detection System in Bangladesh

    Science.gov (United States)

    Moffitt, C. B.

    2009-12-01

    Floods are one of the most destructive natural forces on earth, affecting millions of people annually. Nations lying in the downstream end of an international river basin often suffer the most damage during flooding and could benefit from the real-time communication of rainfall and stream flow data from countries upstream. This is less likely to happen among developing nations due to a lack of freshwater treaties (Balthrop and Hossain, Water Policy, 2009). A more viable option is for flood-prone developing nations to utilize the global satellite rainfall and modeled runoff data that is independently and freely available from the NASA Satellite-based Global Flood Detection System. Although the NASA Global Flood Detection System has been in operation in real-time since 2006, the ‘detection’ capability of flooding has only been validated against qualitative reports in news papers and other types of media. In this study, a more quantitative validation against in-situ measurements of the flood detection system over Bangladesh is presented. Using ground-measured stream flow data as well as satellite-based flood potential and rainfall data, the study looks into the relationship between rainfall and flood potential, rainfall and stream flow, and stream flow and flood potential for three very distinct river systems in Bangladesh - 1) Ganges- a snow-fed river regulated by upstream India 2) Brahmaputra - a snow-fed river that is also braided 3) Meghna - a rain-fed river. The quantitative assessment will show the effectiveness of the NASA Global Flood Detection System for a very humid and flood prone region like Bangladesh that is also faced with tremendous transboundary hurdles that can only be resolved from the vantage of space.

  14. Satellite data compression

    CERN Document Server

    Huang, Bormin

    2011-01-01

    Satellite Data Compression covers recent progress in compression techniques for multispectral, hyperspectral and ultra spectral data. A survey of recent advances in the fields of satellite communications, remote sensing and geographical information systems is included. Satellite Data Compression, contributed by leaders in this field, is the first book available on satellite data compression. It covers onboard compression methodology and hardware developments in several space agencies. Case studies are presented on recent advances in satellite data compression techniques via various prediction-

  15. BeiDou and Galileo, Two Global Satellite Navigation Systems in Final Phase of the Construction, Visibility and Geometry

    Directory of Open Access Journals (Sweden)

    Jacek Januszewski

    2016-09-01

    Full Text Available Spatial segment is one of three segments of each satellite navigation systems (SNS. Nowadays two SNSs, GPS and GLONASS, are fully operational, two next SNSs, BeiDou in China and Galileo in Europe, are in final phase of the construction. In the case of China system this segment will consist of 35 satellites with three types of orbits ? medium (MEO, geostationary (GEO and inclined geosynchronous (IGSO. As GEO and IGSO satellites can be used in China and Asia-Pacific region only, BeiDou MEO constellation with 27 fully operational satellites will be taken into account in this paper. The orbital planes of the Galileo constellation will be divided in “slots” that contains at least one operational satellite. The Galileo reference constellation has 24 nominal orbital positions or operational slots in MEO homogeneously distributed in 3 orbital planes; i.e. 8 slots equally spaced per plane. As the error of user’s position obtained from both systems depends on geometry factor DOP (Dilution Of Precision among other things the knowledge of the number of satellites visible by the user above given masking elevation angle Hmin and the distributions of DOP coefficient values, GDOP in particular, is very important. The lowest and the greatest number of satellites visible in open area by the observer at different latitudes for different Hmin, the percentage of satellites visible above angle H, distributions (in per cent of satellites azimuths and GDOP coefficient values for different Hmin for BeiDou and Galileo systems at different latitudes are presented in the paper.

  16. Large divergence of satellite and Earth system model estimates of global terrestrial CO2 fertilization

    Science.gov (United States)

    Smith, W. Kolby; Reed, Sasha C.; Cleveland, Cory C.; Ballantyne, Ashley P; Anderegg, William R. L.; Wieder, William R.; Liu, Yi Y; Running, Steven W.

    2015-01-01

    Atmospheric mass balance analyses suggest that terrestrial carbon (C) storage is increasing, partially abating the atmospheric [CO2] growth rate, although the continued strength of this important ecosystem service remains uncertain. Some evidence suggests that these increases will persist owing to positive responses of vegetation growth (net primary productivity; NPP) to rising atmospheric [CO2] (that is, ‘CO2 fertilization’). Here, we present a new satellite-derived global terrestrial NPP data set, which shows a significant increase in NPP from 1982 to 2011. However, comparison against Earth system model (ESM) NPP estimates reveals a significant divergence, with satellite-derived increases (2.8 ± 1.50%) less than half of ESM-derived increases (7.6  ±  1.67%) over the 30-year period. By isolating the CO2 fertilization effect in each NPP time series and comparing it against a synthesis of available free-air CO2 enrichment data, we provide evidence that much of the discrepancy may be due to an over-sensitivity of ESMs to atmospheric [CO2], potentially reflecting an under-representation of climatic feedbacks and/or a lack of representation of nutrient constraints. Our understanding of CO2 fertilization effects on NPP needs rapid improvement to enable more accurate projections of future C cycle–climate feedbacks; we contend that better integration of modelling, satellite and experimental approaches offers a promising way forward.

  17. Development of a Hydrogen and Heat Storage System for Satellite Applications

    Science.gov (United States)

    Reissner, Alexander; Pawelke, Roland; Hummel, Stefan; Gerger, Joachim; Lutz, Matthias; Farnes, Jarle; Vik, Arild; Wernhus, Ivar; Svendsen, Tjalve; Schautz, Max; Geneste, Xavier

    2014-08-01

    Next generation telecommunication satellites will demand increasingly more power in the range of 30 kW or more within the next 10 years. Battery technology that can sustain 30 kW for an eclipse length of up to 72 minutes will represent a major impact on the total mass of the satellite, even with new Li-ion battery technologies. Regenerative fuel cell systems (RFCS) were identified years ago as a possible alternative to rechargeable batteries. They consist of a dedicated fuel cell unit for electricity generation and a dedicated electrolyser which regenerates the fuel cell reactants hydrogen and oxygen from the fuel cell reaction product water. All units are integrated in a closed loop system. Nevertheless, one major drawback has been identified by several independent system studies [4,5], namely the need to dissipate large amounts of heat from the fuel cell during Eclipse. This in turn requires massive thermal hardware (mainly large radiators) that can contribute up to 50% of the system mass. FOTEC has suggested the use of metal hydrides as combined hydrogen and heat storage system to overcome this issue and is currently manufacturing a technology demonstrator within an ongoing ESA project. The status of these developments is outlined in this paper.

  18. SYSTEM MODELLING OF DTH BROADCASTING AT KA BAND MULTIBEAM SATELLITE SYSTEM OVER INDIA

    Directory of Open Access Journals (Sweden)

    Swastik Sahoo

    2015-12-01

    Full Text Available A major application of satellite is broadcasting and in India this is done at Ku band. But with the increase of demand of number of channels Ku band is getting saturated. So, to satisfy this requirement an approach is to go to higher frequency band, i.e. Ka band. As India is allocated with seven fixed GEO locations, so the purpose is to calculate what is the suitable satellite position for India at Ka band, what is the best EIRP available at that position and what will be the smallest ground antenna diameter and satellite antenna diameter at Ka band. Broadcasting is done at 20GHz Ka band downlink frequency. At this frequency, as the signal will face lots of impairments during propagation, so the attenuation caused by variety of factors are discussed here. To overcome the attenuation maximum EIRP is given. The link equation is taken as a reference to calculate quality of the signal, G/T ratio and EIRP of the satellite. The extreme west region of India is being taken as earth station and after some brief calculations all the results are discussed. Out of seven allocated GEO locations, 74⁰E gives best output in terms of minimum loss & small antenna diameters.

  19. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2017-01-01

    The first edition of this ground breaking reference work was the most comprehensive reference source available about the key aspects of the satellite applications field. This updated second edition covers the technology, the markets, applications and regulations related to satellite telecommunications, broadcasting and networking—including civilian and military systems; precise satellite navigation and timing networks (i.e. GPS and others); remote sensing and meteorological satellite systems. Created under the auspices of the International Space University based in France, this brand new edition is now expanded to cover new innovative small satellite constellations, new commercial launching systems, innovation in military application satellites and their acquisition, updated appendices, a useful glossary and more.

  20. Cloud parameters using Ground Based Remote Sensing Systems and Satellites over urban coastal area

    Science.gov (United States)

    Han, Z. T.; Gross, B.; Moshary, F.; Wu, Y.; Ahmed, S. A.

    2013-12-01

    Determining cloud radiative and microphysical properties are very important as a means to assess their effect on earths energy balance. While MODIS and GOES have been used for estimating cloud properties, assessing cloud properties directly has been difficult due the lack of consistent ground based sensor measurements except in such established places such as the ARM site in Oklahoma. However, it is known that significant aerosol seeding from urban and/or maritime sources can modify cloud properties such as effective radius and cloud optical depth and therefore evaluation of satellite retrievals in such a unique area offers novel opportunities to assess the potential of satellite retrievals to distinguish these mechanisms In our study, we used a multi-filter rotating shadow band radiometer (MFRSR) and micro wave radiometer (MWR) to retrieve the cloud optical depth and cloud droplets effective radius . In particular, we make a statistical study during summer 2013 where water phase clouds dominate and assess the accuracy of both MODIS and GOES satellite cloud products including LWP, COD and Reff. Most importantly, we assess performance against satellite observing geometries. Much like previous studies at the ARM site, we observe significant biases in the effective radius when the solar zenith angle is too large. In addition, we show that biases are also sensitive to the LWP limiting such measurement s in assessing potential aerosol-cloud signatures Finally, we discuss preliminary aerosol-cloud interactions from our ground system where local lidar is used to assess aerosols below clouds and explore the Aerosol Cloud Index.

  1. Laser-based satellite communication systems stabilized by non-mechanical electro-optic scanners

    Science.gov (United States)

    Ziemkiewicz, Michael; Davis, Scott R.; Rommel, Scott D.; Gann, Derek; Luey, Benjamin; Gamble, Joseph D.; Anderson, Mike

    2016-05-01

    Laser communications systems provide numerous advantages for establishing satellite-to-ground data links. As a carrier for information, lasers are characterized by high bandwidth and directionality, allowing for fast and secure transfer of data. These systems are also highly resistant to RF influences since they operate in the infrared portion of the electromagnetic spectrum, far from radio bands. In this paper we will discuss an entirely non-mechanical electro-optic (EO) laser beam steering technology, with no moving parts, which we have used to form robust 400 Mbps optical data connections through air. This technology will enable low cost, compact, and rugged free space optical (FSO) communication modules for small satellite applications. The EO beam-steerer at the heart of this system is used to maintain beam pointing as the satellite orbits. It is characterized by extremely low values for size, weight and power consumption (SWaP) - approximately 300 cm3, 300 g, and 5 W respectively, which represents a marked improvement compared to heavy, and power-consuming gimbal mechanisms. It is capable of steering a 500 mW, 1 mm short wave infrared (SWIR) beam over a field of view (FOV) of up to 50° x 15°, a range which can be increased by adding polarization gratings, which provide a coarse adjust stage at the EO beam scanner output. We have integrated this device into a communication system and demonstrated the capability to lock on and transmit a high quality data stream by modulation of SWIR power.

  2. Social acceptability of Satellite Power Systems (SPS): the near-term outlook

    Energy Technology Data Exchange (ETDEWEB)

    Klineberg, S L

    1980-05-01

    It is important, at this early stage in the concept development and evaluation of Satellite Power Systems, to explore aspects of contemporary social change that may be expected to complicate the process of achieving the necessary support of the American public for this new technological venture. Current public attitudes make it appear unlikely that a consensus will evolve during the 1980s favoring costly efforts to develop vast new supplies of conventional energy. Opinion polls reveal a pervasive worry over inflation, a broadening of aspirations to encompass quality-of-life concerns, a growing distrust of central governments, large corporations, big science and technology, and a continuing commitment to environmental protection - all of which suggests a social environment that is likely to resist the development of a major new high-technology energy system such as the SPS. Opposition to satellite power will focus on the high front-end development costs, on environmental and technical uncertainties, and on a generalized distrust of large bureaucracies and esoteric technologies. The SPS concept is also likely to be viewed with skepticism by those with vested interests in the long-run uses of coal, shale, fission, fusion, or on-site solar technologies. The growing commitment to energy conservation and the spreading deployment of dispersed renewable-energy systems strongly suggest that the unmet US demand for centrally generated electricity is unlikely to grow sufficiently over the next twenty years to convince a reluctant public of the need for so large an investment of scarce resources in the SPS program. Satellite Power Systems will have a problem in the area of public acceptability.

  3. The Design and Application of Data Storage System in Miyun Satellite Ground Station

    Science.gov (United States)

    Xue, Xiping; Su, Yan; Zhang, Hongbo; Liu, Bin; Yao, Meijuan; Zhao, Shu

    2015-04-01

    China has launched Chang'E-3 satellite in 2013, firstly achieved soft landing on moon for China's lunar probe. Miyun satellite ground station firstly used SAN storage network system based-on Stornext sharing software in Chang'E-3 mission. System performance fully meets the application requirements of Miyun ground station data storage.The Stornext file system is a sharing file system with high performance, supports multiple servers to access the file system using different operating system at the same time, and supports access to data on a variety of topologies, such as SAN and LAN. Stornext focused on data protection and big data management. It is announced that Quantum province has sold more than 70,000 licenses of Stornext file system worldwide, and its customer base is growing, which marks its leading position in the big data management.The responsibilities of Miyun satellite ground station are the reception of Chang'E-3 satellite downlink data and management of local data storage. The station mainly completes exploration mission management, receiving and management of observation data, and provides a comprehensive, centralized monitoring and control functions on data receiving equipment. The ground station applied SAN storage network system based on Stornext shared software for receiving and managing data reliable.The computer system in Miyun ground station is composed by business running servers, application workstations and other storage equipments. So storage systems need a shared file system which supports heterogeneous multi-operating system. In practical applications, 10 nodes simultaneously write data to the file system through 16 channels, and the maximum data transfer rate of each channel is up to 15MB/s. Thus the network throughput of file system is not less than 240MB/s. At the same time, the maximum capacity of each data file is up to 810GB. The storage system planned requires that 10 nodes simultaneously write data to the file system through 16

  4. DETECTION OF THE VELOCITY SHEAR EFFECT ON THE SPATIAL DISTRIBUTIONS OF THE GALACTIC SATELLITES IN ISOLATED SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jounghun [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Choi, Yun-Young, E-mail: jounghun@astro.snu.ac.kr, E-mail: yy.choi@khu.ac.kr [Department of Astronomy and Space Science, Kyung Hee University, Gyeonggi 446-701 (Korea, Republic of)

    2015-02-01

    We report a detection of the effect of the large-scale velocity shear on the spatial distributions of the galactic satellites around the isolated hosts. Identifying the isolated galactic systems, each of which consists of a single host galaxy and its satellites, from the Seventh Data Release of the Sloan Digital Sky Survey and reconstructing linearly the velocity shear field in the local universe, we measure the alignments between the relative positions of the satellites from their isolated hosts and the principal axes of the local velocity shear tensors projected onto the plane of sky. We find a clear signal that the galactic satellites in isolated systems are located preferentially along the directions of the minor principal axes of the large-scale velocity shear field. Those galactic satellites that are spirals, are brighter, are located at distances larger than the projected virial radii of the hosts, and belong to the spiral hosts yield stronger alignment signals, which implies that the alignment strength depends on the formation and accretion epochs of the galactic satellites. It is also shown that the alignment strength is quite insensitive to the cosmic web environment, as well as the size and luminosity of the isolated hosts. Although this result is consistent with the numerical finding of Libeskind et al. based on an N-body experiment, owing to the very low significance of the observed signals, it remains inconclusive whether or not the velocity shear effect on the satellite distribution is truly universal.

  5. Eliminating Obliquity Error from the Estimation of Ionospheric Delay in a Satellite-Based Augmentation System

    Science.gov (United States)

    Sparks, Lawrence

    2013-01-01

    Current satellite-based augmentation systems estimate ionospheric delay using algorithms that assume the electron density of the ionosphere is non-negligible only in a thin shell located near the peak of the actual profile. In its initial operating capability, for example, the Wide Area Augmentation System incorporated the thin shell model into an estimation algorithm that calculates vertical delay using a planar fit. Under disturbed conditions or at low latitude where ionospheric structure is complex, however, the thin shell approximation can serve as a significant source of estimation error. A recent upgrade of the system replaced the planar fit algorithm with an algorithm based upon kriging. The upgrade owes its success, in part, to the ability of kriging to mitigate the error due to this approximation. Previously, alternative delay estimation algorithms have been proposed that eliminate the need for invoking the thin shell model altogether. Prior analyses have compared the accuracy achieved by these methods to the accuracy achieved by the planar fit algorithm. This paper extends these analyses to include a comparison with the accuracy achieved by kriging. It concludes by examining how a satellite-based augmentation system might be implemented without recourse to the thin shell approximation.

  6. NOAA NESDIS global automated satellite-based snow mapping system and products

    Science.gov (United States)

    Romanov, Peter

    2016-05-01

    Accurate, timely and spatially detailed information on the snow cover distribution and on the snow pack properties is needed in various research and practical applications including numerical weather prediction, climate modeling, river runoff estimates and flood forecasts. Owing to the wide area coverage, high spatial resolution and short repeat cycle of observations satellites present one of the key components of the global snow and ice cover monitoring system. The Global Multisensor Automated Snow and Ice Mapping System (GMASI) has been developed at the request of NOAA National Weather Service (NWS) and NOAA National Ice Center (NIC) to facilitate NOAA operational monitoring of snow and ice cover and to provide information on snow and ice for use in NWP models. Since 2006 the system has been routinely generating daily snow and ice cover maps using combined observations in the visible/infrared and in the microwave from operational meteorological satellites. The output product provides continuous (gap free) characterization of the global snow and ice cover distribution at 4 km spatial resolution. The paper presents a basic description of the snow and ice mapping algorithms incorporated in the system as well as of the product generated with GMASI. It explains the approach used to validate the derived snow and ice maps and provides the results of their accuracy assessment.

  7. Developments of satellite radiance assimilation system of AMSU-A within KIAPS-LETKF framework

    Science.gov (United States)

    Kim, Ju-Hye; Kang, Ji-Sun; Jung, Byoung-Joo; Chun, Hyoung-Wook; Lee, Sihye

    2014-05-01

    Korea Institute of Atmospheric Prediction Systems (KIAPS) has successfully implemented Local Ensemble Transform Kalman Filter (LETKF; Hunt et al. 2007) data assimilation system to NCAR CAM-Spectral Element model. This model has the same grid structure on the cubed sphere as KIAPS-Global Model now developing without any singularity, and has a strong advantage on the flexibility and scalability in the future high performance computing environment. The KIAPS-LETKF system (Kang et al. 2013) has also adopted most advanced data assimilation techniques such as an adaptive multiplicative inflation (Miyoshi 2012), an estimation of ensemble forecast sensitivity to observations (EFSO; Kalnay et al. 2012) and proactive quality control (PQC; Ota et al. 2013). With those promising tools in the KIAPS-LETKF system, we plan to assimilate conventional data as well as various remote sensing data such as AMSU-A, IASI, GPS RO, which an observation preprocessing team at KIAPS has processed. In this study, we will present our assimilation strategy of AMSU-A radiance data from NOAA and MetOp satellites and show preliminary results at the conference. As an observation operator for satellite radiance data, the Radiative Transfer Model for the TIROS Operational Vertical Sounder (RTTOV) version 10.2 (Saunders et al. 2012) has been installed.

  8. A system for the simulation and evaluation of satellite communication networks

    Science.gov (United States)

    Bagwell, J. W.

    1984-01-01

    With the emergence of a new era in satellite communications, brought about by NASA's thrust into the Ka band with multibeam and onboard processing technologies, new and innovative techniques for evaluating these concepts and systems are required. To this end, NASA, in conjunction with its extensive program for advanced communications technology development, has undertaken to develop a concept for the simulation and evaluation of a complete communications network. Incorporated in this network will be proof-of-concept models of the latest technologies proposed for future satellite communications systems. These include low noise receivers, matrix switches, baseband processors, and solid state and tube type high power amplifiers. To accomplish this, numerous supporting technologies must be added to those aforementioned proof-of-concept models. These include controllers for synchronization, order wire, resource allocation, gain compensation, signal leveling, power augmentation, and rain fade and range delay simulation. Taken together, these will be assembled to comprise a system capable of addressing numerous design and performance questions. The simulation and evaluation system, as planned, will be modular in design and implementation, capable of modification and updating to track and evaluate a continuum of emerging concepts and technologies. Previously announced in STAR as N84-13400

  9. The Effect of Satellite Observing System Changes on MERRA Water and Energy Fluxes

    Science.gov (United States)

    Robertson, Franklin R.; Bosilovich, M. G.; Chen, J.; Miller, T. L.

    2011-01-01

    Because reanalysis data sets offer state variables and fluxes at regular space / time intervals, atmospheric reanalyses have become a mainstay of the climate community for diagnostic purposes and for driving offline ocean and land models. Although one weakness of these data sets is the susceptibility of the flux products to uncertainties because of shortcomings in parameterized model physics, another issue, perhaps less appreciated, is the fact that continual but discreet changes in the evolving observational system, particularly from satellite sensors, may also introduce artifacts in the time series of quantities. In this paper we examine the ability of the NASA MERRA (Modern Era Retrospective Analysis for Research and Applications) and other recent reanalyses to determine variability in the climate system over the satellite record (approx. the last 30 years). In particular we highlight the effect on the reanalysis of discontinuities at the junctures of the onset of passive microwave imaging (Special Sensor Microwave Imager) in late 1987 and, more prominently, with improved sounding and imaging with the Advanced Microwave Sounding Unit, AMSU-A, in 1998. We first examine MERRA fluxes from the perspective of how physical modes of variability (e.g. ENSO events, Pacific Decadal Variability) are contained by artificial step-like trends induced by the onset of new moisture data these two satellite observing systems. Secondly, we show how Redundancy Analysis, a statistical regression methodology, is effective in relating these artifact signals in the moisture and temperature analysis increments to their presence in the physical flux terms (e.g. precipitation, radiation). This procedure is shown to be effective greatly reducing the artificial trends in the flux quantities.

  10. The Effect of Satellite Observing System Changes on MERRA Water and Energy Fluxes

    Science.gov (United States)

    Robertson, F. R.; Bosilovich, M. G.; Chen, J.; Miller, T. L.

    2010-12-01

    Because reanalysis data sets offer state variables and fluxes at regular space / time intervals, these products have become a mainstay of the climate community for diagnostic purposes and for driving offline ocean and land models. Although one weakness of these data sets is the susceptibility of the flux products to uncertainties because of shortcomings in parameterized model physics, another issue, perhaps less appreciated, is the fact that continual but discreet changes in the evolving observational system, particularly from satellite sensors, may also introduce artifacts in the time series of quantities. In this paper we examine the ability of the NASA MERRA (Modern Era Retrospective Analysis for Research and Applications) to determine variability in the climate system over the satellite record (~ the last 30 years). In particular we highlight the effect on the reanalysis of discontinuities at the onset of passive microwave imaging (Special Sensor Microwave Imager, SSMI) in late 1987 as well as improved sounding and imaging with the Advanced Microwave Sounding Unit, AMSU-A, in 1998. We first examine MERRA fluxes from the perspective of how physical modes of variability (e.g. ENSO events, Pacific Decadal Variability) are contamined by artificial step-like trends induced by the onset of new moisture data these two satellite observing systems. Secondly, we show how Redundancy Analysis, a statistical regression methodology, is effective in relating these artifact signals in the moisture and temperature analysis increments to their presence in the physical flux terms (e.g. precipitation, radiation). This procedure is shown to be effective greatly reducing the artificial trends in the flux quantities.

  11. Payload Service System for the Small Satellites of Double Star Project

    Science.gov (United States)

    Sun, H. X.; Chen, X. M.

    Double Star Project (DSP) is a cooperative program between ESA and China, which plan to be launched in 2003. The main objective of the program is to explore the magnetosphere of the earth. Using two small satellites, one is in near polar orbit, another is in near equatorial orbit; compensate CLUSTER II 4 satellites, to form 6 points measurements and to detect the 3-D small-scale structures and spatial-temporal variations of magnetosphere. ESA will provide several experiment payloads, which are identical to that of CLUSTER II, include Fluxgate Magnetometer (FGM), Active Spacecraft Potential Control experiment (ASPOC), Spatial- Temporal Analysis of Field Fluctuation experiment (STAFF), Plasma Electron And Current Experiment (PEACE), Hot Ion Analyzer (HIA) etc. China will provide the launcher, the satellite platform and several experiment payloads, include Heave Ion Detector (HID), High Energy Electron Detector (HEED), High Energy Proton Detector (HEPD), Low Frequency Electromagnetic Wave Detector etc. In order to reduce the cost, all the experiment payloads provided by ESA keep the same with that of CLUSTER II, include all interfaces even for data acquisition sequence. However the satellites and the interfaces of the payloads from China are different form CLUSTER II, so how to handle the data of the experiments became a challenge problem for the DSP. CSSAR designed a Payload Service System (PSS) to bridge the gap. PSS is a distributed system based on the 1553B data bus, it is consist of Bus Controller, Soiled State Recorder, High Rate Multiplexer, Remote Terminal, S-band Transmitter and Power Distributor. In Bus Controller the special interface designed to connect the ESA experiment payloads, which follow the same interface standard with CLUSTER II. All other payloads and instruments access the system via 1553B data bus. PSS acquire the science and housekeeping data of ESA experiments with the same sequence and period as they did in CLUSTER II, but the data will be

  12. High Accuracy Attitude Control System Design for Satellite with Flexible Appendages

    Directory of Open Access Journals (Sweden)

    Wenya Zhou

    2014-01-01

    Full Text Available In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on the attitude control system, the structural filter is designed in terms of rejecting the vibration of flexible appendages. Considering the potential problem of in-orbit frequency variation of the flexible appendages, the design method for the adaptive notch filter is proposed based on the in-orbit identification technology. Finally, the simulation results are given to demonstrate the feasibility and effectiveness of the proposed design techniques.

  13. Reduced Toxicity Fuel Satellite Propulsion System Including Catalytic Decomposing Element with Hydrogen Peroxide

    Science.gov (United States)

    Schneider, Steven J. (Inventor)

    2002-01-01

    A reduced toxicity fuel satellite propulsion system including a reduced toxicity propellant supply for consumption in an axial class thruster and an ACS class thruster. The system includes suitable valves and conduits for supplying the reduced toxicity propellant to the ACS decomposing element of an ACS thruster. The ACS decomposing element is operative to decompose the reduced toxicity propellant into hot propulsive gases. In addition the system includes suitable valves and conduits for supplying the reduced toxicity propellant to an axial decomposing element of the axial thruster. The axial decomposing element is operative to decompose the reduced toxicity propellant into hot gases. The system further includes suitable valves and conduits for supplying a second propellant to a combustion chamber of the axial thruster, whereby the hot gases and the second propellant auto-ignite and begin the combustion process for producing thrust.

  14. A simplified satellite navigation system for an autonomous Mars roving vehicle.

    Science.gov (United States)

    Janosko, R. E.; Shen, C. N.

    1972-01-01

    The use of a retroflecting satellite and a laser rangefinder to navigate a Martian roving vehicle is considered in this paper. It is shown that a simple system can be employed to perform this task. An error analysis is performed on the navigation equations and it is shown that the error inherent in the scheme proposed can be minimized by the proper choice of measurement geometry. A nonlinear programming approach is used to minimize the navigation error subject to constraints that are due to geometric and laser requirements. The problem is solved for a particular set of laser parameters and the optimal solution is presented.

  15. A 20 GHz low noise, low cost receiver for digital satellite communication system, ground terminal applications

    Science.gov (United States)

    Allen, Glen

    1988-01-01

    A 45 month effort for the development of a 20 GHz, low-noise, low-cost receiver for digital, satellite communication system, ground terminal applications is discussed. Six proof-of-concept receivers were built in two lots of three each. Performance was generally consistent between the two lots. Except for overall noise figure, parameters were within or very close to specification. While noise figure was specified as 3.5 dB, typical performance was measured at 3.0 to 5.5 dB, over the full temperature range of minus 30 C to plus 75 C.

  16. Joint Polar Satellite System (JPSS) Micrometeoroid and Orbital Debris (MMOD) Assessment

    Science.gov (United States)

    Squire, Michael D.; Cooke, William J.; Williamsen, Joel; Kessler, Donald; Vesely, William E.; Hull, Scott H.; Schonberg, William; Peterson, Glenn E.; Jenkin, Alan B.; Cornford, Steven L.

    2015-01-01

    The Joint Polar Satellite System (JPSS) Project requested the NASA Engineering and Safety Center (NESC) conduct an independent evaluation of the Micrometeoroid and Orbital Debris (MMOD) models used in the latest JPSS MMOD risk assessment. The principal focus of the assessment was to compare Orbital Debris Engineering Model version 3 (ORDEM 3.0) with the Meteoroid and Space Debris Terrestrial Environment Reference version 2009 (MASTER-2009) and Aerospace Debris Environment Projection Tool (ADEPT) and provide recommendations to the JPSS Project regarding MMOD protection. The outcome of the NESC assessment is contained in this report.

  17. Numerical arc segmentation algorithm for a radio conference - A software tool for communication satellite systems planning

    Science.gov (United States)

    Whyte, W. A.; Heyward, A. O.; Ponchak, D. S.; Spence, R. L.; Zuzek, J. E.

    1988-01-01

    A detailed description of a Numerical Arc Segmentation Algorithm for a Radio Conference (NASARC) software package for communication satellite systems planning is presented. This software provides a method of generating predetermined arc segments for use in the development of an allotment planning procedure to be carried out at the 1988 World Administrative Radio Conference (WARC - 88) on the use of the GEO and the planning of space services utilizing GEO. The features of the NASARC software package are described, and detailed information is given about the function of each of the four NASARC program modules. The results of a sample world scenario are presented and discussed.

  18. The Global Land Surface Satellite (GLASS Remote Sensing Data Processing System and Products

    Directory of Open Access Journals (Sweden)

    Gongqi Zhou

    2013-05-01

    Full Text Available Using remotely sensed satellite products is the most efficient way to monitor global land, water, and forest resource changes, which are believed to be the main factors for understanding global climate change and its impacts. A reliable remotely sensed product should be retrieved quantitatively through models or statistical methods. However, producing global products requires a complex computing system and massive volumes of multi-sensor and multi-temporal remotely sensed data. This manuscript describes the ground Global LAnd Surface Satellite (GLASS product generation system that can be used to generate long-sequence time series of global land surface data products based on various remotely sensed data. To ensure stabilization and efficiency in running the system, we used the methods of task management, parallelization, and multi I/O channels. An array of GLASS remote sensing products related to global land surface parameters are currently being produced and distributed by the Center for Global Change Data Processing and Analysis at Beijing Normal University in Beijing, China. These products include Leaf Area Index (LAI, land surface albedo, and broadband emissivity (BBE from the years 1981 to 2010, downward shortwave radiation (DSR and photosynthetically active radiation (PAR from the years 2008 to 2010.

  19. Study of the triple-mass Tethered Satellite System under aerodynamic drag and J2 perturbations

    Science.gov (United States)

    Razzaghi, Pourya; Assadian, Nima

    2015-11-01

    The dynamics of multi-tethered satellite formations consisting of three masses are studied in this paper. The triple-mass triple-tethered satellite system is modeled under the low Earth orbit perturbations of drag and Earth's oblateness and its equilibrium conditions are derived. It is modeled as three equal end-masses connected by a uniform-mass straight tether. The lengths of tethers are supposed to be constant and in this manner the angles of the plane consisting the masses are taken as the state variables of the system. The governing equations of motion are derived using Lagrangian approach. The aerodynamic drag perturbation is expressed as an external non-conservative force and the Earth oblateness (J2 perturbation) is considered as a term of potential energy. The equilibrium conditions of this system are found and their stability is investigated through the linear stability theory. Then, the results are verified by using a nonlinear simulation for three types of equilibrium conditions.

  20. Blind Equalization of a Nonlinear Satellite System Using MCMC Simulation Methods

    Directory of Open Access Journals (Sweden)

    Sénécal Stéphane

    2002-01-01

    Full Text Available This paper proposes the use of Markov Chain Monte-Carlo (MCMC simulation methods for equalizing a satellite communication system. The main difficulties encountered are the nonlinear distorsions caused by the amplifier stage in the satellite. Several processing methods manage to take into account the nonlinearity of the system but they require the knowledge of a training/learning input sequence for updating the parameters of the equalizer. Blind equalization methods also exist but they require a Volterra modelization of the system. The aim of the paper is also to blindly restore the emitted message. To reach the goal, we adopt a Bayesian point of view. We jointly use the prior knowledge on the emitted symbols, and the information available from the received signal. This is done by considering the posterior distribution of the input sequence and the parameters of the model. Such a distribution is very difficult to study and thus motivates the implementation of MCMC methods. The presentation of the method is cut into two parts. The first part solves the problem for a simplified model; the second part deals with the complete model, and a part of the solution uses the algorithm developed for the simplified model. The algorithms are illustrated and their performance is evaluated using bit error rate versus signal-to-noise ratio curves.

  1. Optimization design of satellite separation systems based on Multi-Island Genetic Algorithm

    Science.gov (United States)

    Hu, Xingzhi; Chen, Xiaoqian; Zhao, Yong; Yao, Wen

    2014-03-01

    The separation systems are crucial for the launch of satellites. With respect to the existing design issues of satellite separation systems, an optimization design approach based on Multi-Island Genetic Algorithm is proposed, and a hierarchical optimization of system mass and separation angular velocity is designed. Multi-Island Genetic Algorithm is studied for the problem and the optimization parameters are discussed. Dynamic analysis of ADAMS used to validate the designs is integrated with iSIGHT. Then the optimization method is employed for a typical problem using the helical compression spring mechanism, and the corresponding objective functions are derived. It turns out that the mass of compression spring catapult is decreased by 30.7% after optimization and the angular velocity can be minimized considering spring stiffness errors. Moreover, ground tests and on-orbit flight indicate that the error of separation speed is controlled within 1% and the angular velocity is reduced by nearly 90%, which proves the design result and the optimization approach.

  2. Real-time horizontality adjusting and control system of a large platform applied to satellite experiment

    Institute of Scientific and Technical Information of China (English)

    ZHONG Shi-sheng; ZHANG Shi-peng; WANG Rui

    2007-01-01

    In order to satisfy a satellite horizontality requirement in an experiment, it is indispensable to monitor and adjust the horizontality of a large platform loading the satellite under the condition of ultra-low temperature with real time. So the control system design and control strategy are described in detail to accomplish the horizontality monitoring and adjusting. The system adopts the industry control computer as the upper computer and the SIEMENS S7-300 PLC as the lower computer. The upper computer that bases on industry configuration software IFIX takes charge of monitoring the platform and puts forward the control strategy. PLC takes charge of receiving the adjusting instructions and controlling the legs moving to accomplish the horizontality adjusting. The horizontality adjusting strategy is emphasized and the concept of grads is introduced to establish a mathematics model of the platform inclined state, so the adjusting method is obtained. Accordingly the key question of the automatic horizontality adjusting is solved in this control system.

  3. Detecting extrasolar moons akin to Solar System satellites with an Orbital Sampling Effect

    CERN Document Server

    Heller, René

    2014-01-01

    Despite years of high accuracy observations, none of the available theoretical techniques has yet allowed the confirmation of a moon beyond the Solar System. Methods are currently limited to masses about an order of magnitude higher than the mass of any moon in the Solar System. I here present a new method sensitive to exomoons similar to the known moons. Due to the projection of transiting exomoon orbits onto the celestial plane, satellites appear more often at larger separations from their planet. After about a dozen randomly sampled observations, a photometric orbital sampling effect (OSE) starts to appear in the phase-folded transit light curve, indicative of the moons' radii and planetary distances. Two additional outcomes of the OSE emerge in the planet's transit timing variations (TTV-OSE) and transit duration variations (TDV-OSE), both of which permit measurements of a moon's mass. The OSE is the first effect that permits characterization of multi-satellite systems. I derive and apply analytical OSE d...

  4. DVB-RCS return link radio resource management for broadband satellite systems using fade mitigation techniques at ka band

    OpenAIRE

    2008-01-01

    Current Broadband Satellite systems supporting DVB-RCS at Ku band have static physical layer in order not to complicate their implementation. However at Ka band frequencies and above an adaptive physical layer wherein the physical layer parameters are dynamically modified on a per user basis is necessary to counteract atmospheric attenuation. Satellite Radio Resource Management (RRM) at the Medium Access Control (MAC) layer has become an important issue given the emphasis placed on Quality...

  5. The Spectral Classes of the Saturnian System Ices: Rings and Satellites Observations by Cassini-VIMS

    Science.gov (United States)

    Filacchione, G.; Capaccioni, F.; Tosi, F.; Coradini, A.; Cerroni, P.; Clark, R. N.; Cuzzi, J. N.; Nicholson, P. D.; Buratti, B. J.; Brown, R. H.; Cruikshank, D. P.; Jaumann, R.; Hedman, M. M.

    2008-12-01

    The entire population of the Saturnian system ices was investigated by VIMS (Visual and Infrared Mapping Spectrometer) experiment on board Cassini spacecraft. By the end of the nominal mission a very large dataset of hyperspectral data had been collected in the spectral range 0.35-5.0 micron, which includes the regular satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus, Phoebe), minor moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso) and rings. In this work we present an analysis of spectrophotometric indicators selected to describe the properties of the ices (I/F continuum levels, visible spectral slopes, band depths and positions), and which were retrieved from about 1500 full-disk observations of satellites as well as from mosaics of the main rings (A, B, C, CD, F) sampled with a resolution of 125 km/pixel along the radial axis. This comparative method allows us to highlight the spectral differences in this population of objects orbiting in the Saturnian system. In particular we have retrieved the distribution of the water ice abundance, which varies between the almost pure icy surfaces of Enceladus and Calypso to the carbon dioxide- and organic-rich Hyperion, Iapetus and Phoebe. Noteworthy is that a significant dichotomy is observed between the two co-orbital moons Epimetheus and Janus, possibly indicating a different origin and evolutionary process: while the first shows a very red visible spectrum (similar to Hyperion), the second has more neutral visible colors, making it a very peculiar object in the Saturnian system. Rings have very peculiar spectral differences when compared with the icy satellites: in the visible range their spectra are characterized by a spectral knee at bluer wavelengths (at about 520 nm compared to 550 nm on satellites); in the infrared range the 1.5-2.0 micron water ice band depths are in general deeper across the A and B rings, indicative of a larger fraction of pure water ice in comparison to

  6. An automated fog monitoring system for the Indo-Gangetic Plains based on satellite measurements

    Science.gov (United States)

    Patil, Dinesh; Chourey, Reema; Rizvi, Sarwar; Singh, Manoj; Gautam, Ritesh

    2016-05-01

    Fog is a meteorological phenomenon that causes reduction in regional visibility and affects air quality, thus leading to various societal and economic implications, especially disrupting air and rail transportation. The persistent and widespread winter fog impacts the entire the Indo-Gangetic Plains (IGP), as frequently observed in satellite imagery. The IGP is a densely populated region in south Asia, inhabiting about 1/6th of the world's population, with a strong upward pollution trend. In this study, we have used multi-spectral radiances and aerosol/cloud retrievals from Terra/Aqua MODIS data for developing an automated web-based fog monitoring system over the IGP. Using our previous and existing methodologies, and ongoing algorithm development for the detection of fog and retrieval of associated microphysical properties (e.g. fog droplet effective radius), we characterize the widespread fog detection during both daytime and nighttime. Specifically, for the night time fog detection, the algorithm employs a satellite-based bi-spectral brightness temperature difference technique between two spectral channels: MODIS band-22 (3.9μm) and band-31 (10.75μm). Further, we are extending our algorithm development to geostationary satellites, for providing continuous monitoring of the spatial-temporal variation of fog. We anticipate that the ongoing and future development of a fog monitoring system would be of assistance to air, rail and vehicular transportation management, as well as for dissemination of fog information to government agencies and general public. The outputs of fog detection algorithm and related aerosol/cloud parameters are operationally disseminated via http://fogsouthasia.com/.

  7. Pi-Sat: A Low Cost Small Satellite and Distributed Spacecraft Mission System Test Platform

    Science.gov (United States)

    Cudmore, Alan

    2015-01-01

    Current technology and budget trends indicate a shift in satellite architectures from large, expensive single satellite missions, to small, low cost distributed spacecraft missions. At the center of this shift is the SmallSatCubesat architecture. The primary goal of the Pi-Sat project is to create a low cost, and easy to use Distributed Spacecraft Mission (DSM) test bed to facilitate the research and development of next-generation DSM technologies and concepts. This test bed also serves as a realistic software development platform for Small Satellite and Cubesat architectures. The Pi-Sat is based on the popular $35 Raspberry Pi single board computer featuring a 700Mhz ARM processor, 512MB of RAM, a flash memory card, and a wealth of IO options. The Raspberry Pi runs the Linux operating system and can easily run Code 582s Core Flight System flight software architecture. The low cost and high availability of the Raspberry Pi make it an ideal platform for a Distributed Spacecraft Mission and Cubesat software development. The Pi-Sat models currently include a Pi-Sat 1U Cube, a Pi-Sat Wireless Node, and a Pi-Sat Cubesat processor card.The Pi-Sat project takes advantage of many popular trends in the Maker community including low cost electronics, 3d printing, and rapid prototyping in order to provide a realistic platform for flight software testing, training, and technology development. The Pi-Sat has also provided fantastic hands on training opportunities for NASA summer interns and Pathways students.

  8. UAS Satellite Earth Station Emission Limits for Terrestrial System Interference Protection

    Science.gov (United States)

    Kerczewski, Robert J.; Bishop, William D.

    2017-01-01

    Unmanned aircraft systems (UAS) will have a major impact on future aviation. Medium and large UA operating at altitudes above 3000 feet will require access to non-segregated, that is, controlled airspace. In order for unmanned aircraft to be integrated into the airspace and operate with other commercial aircraft, a very reliable command and control (C2, a. k. a. control and non-payload communications, (CNPC)) link is required. For operations covering large distances or over remote locations, a beyond-line-of-sight (BLOS) CNPC link would need to be implemented through satellite. Significant progress has taken place on several fronts to advance the integration of UAS into controlled airspace, including the recent completion of Minimum Operational Performance Standards (MOPS) for terrestrial line-of-sight (LOS) UAS command and control (C2) links. The development of MOPS for beyond line-of-sight C2 satellite communication links is underway. Meanwhile the allocation of spectrum for UAS C2 by the International Telecommunications Union Radiocommunication Sector (ITU-R) has also progressed. Spectrum for LOS C2 was allocated at the 2012 World Radiocommunication Conference (WRC-12), and for BLOS C2 an allocation was made at WRC-15, under WRC-15 Resolution 155. Resolution 155, however, does not come into effect until several other actions have been completed. One of these required actions is the identification of a power flux density (pfd) limit on the emissions of UAS Ku-Band satellite communications transmitters reaching the ground. The pfd limit is intended to protect terrestrial systems from harmful interference. WRC-19 is expected to finalize the pfd limit. In preparation for WRC-19, analyses of the required pfd limit are on-going, and supporting activities such as propagation modeling are also planned. This paper provides the status of these activities.

  9. An Autonomous System to Take Angular Thermal-Infrared Measurements for Validating Satellite Products

    Directory of Open Access Journals (Sweden)

    Raquel Niclòs

    2015-11-01

    Full Text Available An autonomous system for field land surface temperature (LST measurements taken at different observation angles was developed to be deployed easily at any conventional meteorological tower station. The system permits ground-truth data to be acquired on a continuous basis, and angularly scans land and sky hemispheres with a single thermal-infrared (TIR radiometer. This paper describes the autonomous angular system and the methodology to assess ground-truth LST and relative-to-nadir emissivity data from system measurements. Ground-truth LSTs were used to validate satellite-retrieved LST products at two experimental sites (rice crop and shrubland areas. The relative-to-nadir emissivity values were used to analyze the anisotropy of surface emissive properties over thermally-homogeneous covers. The EOS-MODIS MOD11_L2/MYD11_L2 LST product was evaluated and shown to work within expected uncertainties (<2.0 K when tested against the system data. A slight underestimation of around −0.15 K was observed, which became greater for the off-nadir observation angles at the shrubland site. The system took angular measurements for the different seasonal homogeneous covers at the rice crop site. These measurements showed emissivity angular anisotropies, which were in good agreement with previously published data. The dual-view ENVISAT-AATSR data reproduced them, and revealed that the system data collected for thermally-homogeneous surfaces could be used to test future satellite TIR sensors with multi-angular or bi-angular capabilities, like the forthcoming SLSTR on board Copernicus Sentinel-3A.

  10. Adaptive Hierarchical Sliding Mode Control with Input Saturation for Attitude Regulation of Multi-satellite Tethered System

    Science.gov (United States)

    Ma, Zhiqiang; Sun, Guanghui

    2017-06-01

    This paper proposes a novel adaptive hierarchical sliding mode control for the attitude regulation of the multi-satellite inline tethered system, where the input saturation is taken into account. The governing equations for the attitude dynamics of the three-satellite inline tethered system are derived firstly by utilizing Lagrangian mechanics theory. Considering the fact that the attitude of the central satellite can be adjusted by using the simple exponential stabilization scheme, the decoupling of the central satellite and the terminal ones is presented, and in addition, the new adaptive sliding mode control law is applied to stabilize the attitude dynamics of the two terminal satellites based on the synchronization and partial contraction theory. In the adaptive hierarchical sliding mode control design, the input is modeled as saturated input due to the fact that the flywheel torque is bounded, and meanwhile, an adaptive update rate is introduced to eliminate the effect of the saturated input and the external perturbation. The proposed control scheme can be applied on the two-satellite system to achieve fixed-point rotation. Numerical results validate the effectiveness of the proposed method.

  11. Adaptive Hierarchical Sliding Mode Control with Input Saturation for Attitude Regulation of Multi-satellite Tethered System

    Science.gov (United States)

    Ma, Zhiqiang; Sun, Guanghui

    2016-11-01

    This paper proposes a novel adaptive hierarchical sliding mode control for the attitude regulation of the multi-satellite inline tethered system, where the input saturation is taken into account. The governing equations for the attitude dynamics of the three-satellite inline tethered system are derived firstly by utilizing Lagrangian mechanics theory. Considering the fact that the attitude of the central satellite can be adjusted by using the simple exponential stabilization scheme, the decoupling of the central satellite and the terminal ones is presented, and in addition, the new adaptive sliding mode control law is applied to stabilize the attitude dynamics of the two terminal satellites based on the synchronization and partial contraction theory. In the adaptive hierarchical sliding mode control design, the input is modeled as saturated input due to the fact that the flywheel torque is bounded, and meanwhile, an adaptive update rate is introduced to eliminate the effect of the saturated input and the external perturbation. The proposed control scheme can be applied on the two-satellite system to achieve fixed-point rotation. Numerical results validate the effectiveness of the proposed method.

  12. CAPS satellite spread spectrum communication blind multi-user detecting system based on chaotic sequences

    Institute of Scientific and Technical Information of China (English)

    LEI LiHua; SHI HuLi; MA GuanYi

    2009-01-01

    Multiple Path Interference (MPI) and Multiple Access Interference (MAI) are Important factors that affect the performance of Chinese Area Positioning System (CAPS),These problems can be solved by using spreading sequences with ideal properties and multi-user detectors.Chaotic sequences based on Chebyshev map are studied and the satellite communication system model is set up to investigate the application of chaotic sequences for CAPS in this paper,Simulation results show that chaotic sequences have desirable correlation properties and it is easy to generate a large number of chaotic sequences with good security.It has great practical value to apply chaotic sequences to CAPS together with multi-user detecting technology and the system performance can be improved greatly.

  13. The Transverse velocity of the Andromeda system, derived from the M31 satellite population

    CERN Document Server

    Salomon, J -B; Famaey, B; Martin, N F; Lewis, G F

    2015-01-01

    We present a dynamical measurement of the tangential motion of the Andromeda system, the ensemble consisting of the Andromeda Galaxy (M31) and its satellites. The system is modelled as a structure with cosmologically-motivated velocity dispersion and density profiles, and we show that our method works well when tested using the most massive substructures in high-resolution {\\Lambda} Cold Dark Matter ({\\Lambda}CDM) simulations. Applied to the sample of 40 currently-known galaxies of this system, we find a value for the transverse velocity of 164.4 +/- 61.8 km/s (v_{East} = -111.5 +/- 70.2 km/s and v{North} = 99.4 +/- 60.0 km/s), significantly higher than previous estimates of the proper motion of M31 itself. This result has significant implications on estimates of the mass of the Local Group, as well as on its past and future history.

  14. CAPS satellite spread spectrum communication blind multi-user detecting system based on chaotic sequences

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Multiple Path Interference (MPI) and Multiple Access Interference (MAI) are important factors that affect the performance of Chinese Area Positioning System (CAPS). These problems can be solved by using spreading sequences with ideal properties and multi-user detectors. Chaotic sequences based on Chebyshev map are studied and the satellite communication system model is set up to investigate the application of chaotic sequences for CAPS in this paper. Simulation results show that chaotic sequences have desirable correlation properties and it is easy to generate a large number of chaotic sequences with good security. It has great practical value to apply chaotic sequences to CAPS together with multi-user detecting technology and the system performance can be improved greatly.

  15. Information management system: A summary discussion. [for use in the space shuttle sortie, modular space station and TDR satellite

    Science.gov (United States)

    Sayers, R. S.

    1972-01-01

    An information management system is proposed for use in the space shuttle sortie, the modular space station, the tracking data relay satellite and associated ground support systems. Several different information management functions, including data acquisition, transfer, storage, processing, control and display are integrated in the system.

  16. The Role of Satellite Data for the National Forest Monitoring Systems in the Context of REDD+

    Science.gov (United States)

    Jonckheere, Inge

    2012-04-01

    Reducing Emissions from Deforestation and Forest Degradation (REDD) is an effort to create a financial value for the carbon stored in forests, offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. “REDD+” goes beyond deforestation and forest degradation, and includes the role of conservation, sustainable management of forests and enhancement of forest carbon stocks. In the framework of getting countries ready for REDD+, the UN-REDD Programme assists developing countries to prepare and implement national REDD+ strategies. For the monitoring, reporting and verification (MRV), FAO supports the countries to develop national forest monitoring systems (NFMS) based on satellite data that allow for credible MRV of REDD+ activities through time. The UN-REDD Programme through a joint effort of FAO and Brazil's National Space Agency, INPE, is supporting countries to develop cost- effective, robust and compatible national monitoring and MRV systems, providing tools, methodologies, training and knowledge sharing that help countries to strengthen their technical and institutional capacity for effective MRV systems. The Brazilian forest monitoring system, TerraAmazon, which is used as a multi-user basis, allows countries to adapt it to country needs. With the technical assistance of FAO, INPE and other stakeholders, the countries will set up an autonomous operational satellite forest monitoring systems. A beta version and the methodologies of the system for DRC and PNG are launched in Durban (SA) during COP 17, while Paraguay, Zambia and Viet Nam are in development in 2012.

  17. Fade measurements at L-band and UHF in mountainous terrain for land mobile satellite systems

    Science.gov (United States)

    Vogel, Wolfhard J.; Goldhirsh, Julius

    1988-01-01

    Fading results related to land mobile satellite communications at L-band (1502 MHz) and UHF (870 MHz) are described. These results were derived from an experiment performed in a series of canyon passes in the Boulder, Colorado region of the US. The experimental configuration involved a helicopter as the source platform, which maintained a relatively fixed geometry with a mobile van containing the receiver and data-acquisition system. An unobstructed line of sight between the radiating sources and the receiving van was, for the most part, also maintained. In this configuration, the dominant mechanism causing signal fading (or enhancement) is a result of multipath. The resulting fade distributions demonstrated that at the 1 percent and 5 percent levels, 5.5- and 2.6-dB fades were on the average exceeded at L-band and 4.8- and 2.4-dB at UHF, respectively, for a path elevation angle of 45 deg. The canyon results as compared with previous roadside-tree-shadowing results demonstrate that the deciding factor dictating fade margin for future land mobile satellite systems is tree shadowing rather than fades caused by multipath.

  18. Optimal satellite sampling to resolve global-scale dynamics in the I-T system

    Science.gov (United States)

    Rowland, D. E.; Zesta, E.; Connor, H. K.; Pfaff, R. F., Jr.

    2016-12-01

    The recent Decadal Survey highlighted the need for multipoint measurements of ion-neutral coupling processes to study the pathways by which solar wind energy drives dynamics in the I-T system. The emphasis in the Decadal Survey is on global-scale dynamics and processes, and in particular, mission concepts making use of multiple identical spacecraft in low earth orbit were considered for the GDC and DYNAMIC missions. This presentation will provide quantitative assessments of the optimal spacecraft sampling needed to significantly advance our knowledge of I-T dynamics on the global scale.We will examine storm time and quiet time conditions as simulated by global circulation models, and determine how well various candidate satellite constellations and satellite schemes can quantify the plasma and neutral convection patterns and global-scale distributions of plasma density, neutral density, and composition, and their response to changes in the IMF. While the global circulation models are data-starved, and do not contain all the physics that we might expect to observe with a global-scale constellation mission, they are nonetheless an excellent "starting point" for discussions of the implementation of such a mission. The result will be of great utility for the design of future missions, such as GDC, to study the global-scale dynamics of the I-T system.

  19. Ionizing radiation risks to Satellite Power Systems (SPS) workers in space

    Energy Technology Data Exchange (ETDEWEB)

    1980-12-01

    A reference Satellite Power System (SPS) has been designed by NASA and its contractors for the purposes of evaluating the concept and carrying out assessments of the various consequences of development, including those on the health of the space workers. The Department of Energy has responsibility for directing various assessments. Present planning calls for the SPS workers to move from Earth to a low earth orbit (LEO) at an altitude of 500 kilometers; to travel by a transfer ellipse (TE) trajectory to a geosynchronous orbit (GEO) at an altitude of 36,000 kilometers; and to remain in GEO orbit for about 90 percent of the total time aloft. The radiation risks to the health of workers who will construct and maintain solar power satellites in the space environment are studied. The charge to the committee was: (a) to evaluate the radiation environment estimated for the Reference System which could represent a hazard; (b) to assess the possible somatic and genetic radiation hazards; and (c) to estimate the risks to the health of SPS workers due to space radiation exposure, and to make recommendations based on these conclusions. Details are presented. (WHK)

  20. Satellite communication engineering

    CERN Document Server

    Kolawole, Michael Olorunfunmi

    2013-01-01

    An undeniably rich and thorough guide to satellite communication engineering, Satellite Communication Engineering, Second Edition presents the fundamentals of information communications systems in a simple and succinct way. This book considers both the engineering aspects of satellite systems as well as the practical issues in the broad field of information transmission. Implementing concepts developed on an intuitive, physical basis and utilizing a combination of applications and performance curves, this book starts off with a progressive foundation in satellite technology, and then moves on